Alderton's naked body was found in woodland near Ipswich, eastern England, on December 10. She was three months pregnant and had been strangled.

The other dead women, whose bodies were found in villages around the town over a 10-day period, have been identified as Gemma Adams, 25, Tania Nicol, 19, Paula Clennell, 24, and Annette Nicholls, 29.

The cause of death has only been established in one other case -- Clennell died of "compression to the neck," police say.

Officers believe Alderton's body had been in the woods since at least December 7, when a passing motorist is believed to have mistaken it for a mannequin.

In one of Britain's biggest-ever murder hunts, 350 officers from 31 police forces around the country, including Northern Ireland, have been drafted in to help the local force solve the murders.

Jacqui Cheer, Suffolk's assistant chief constable, told BBC radio that police were now close to establishing the last time the women were seen, which was key to resolving the case.

"A good way to describe the progress we are making would be to compare the investigation to a jigsaw," she said.

"We have constructed the edges, now we have to fill in the middle."

Cheer added that officers were "looking at 50 to 100 suspects."

Detective Chief Superintendent Stewart Gull, leading the investigation, has said that nobody has been spoken to as a suspect, despite media reports that officers were homing in on five people.

He added that all the women were found naked, but none showed signs of being subjected to "significant trauma" or "serious sexual assault," fueling speculation that the murderer or murderers might have drugged them.

"It's possible we're looking for the same individual, but there may be more involved. We have to keep an open mind," Gull said, despite widespread media reports that officers are hunting a serial killer.

Police were searching a railway line near where two of the bodies were found Saturday and are also trawling through about 9,000 calls which have been received from the public.

Meanwhile, 25,000 football fans at Ipswich Town's ground, in the heart of the red light district, mourned the five dead women before Saturday's Championship match with Leeds United.

Messages were flashed up on scoreboards and read out on the public address system urging them to contact police if they had any information.

They observed a minute's silence and said prayers for the victims.

"In silence we pray for the five women who died," Richard Lewis, the area's Church of England bishop who was leading prayers at the ground, said.

"These events bring to mind the events in Yorkshire some 25 years ago."

Many have compared the killings to those committed by the "Yorkshire Ripper" Peter Sutcliffe, convicted of the deaths of 13 women between 1975 and 1980, and the notorious Jack the Ripper, who murdered five east London prostitutes in 1888.

People in Ipswich, a usually quiet market town about 80 miles (130 kilometres) northeast of London, have been stunned by the deaths.

The town's streets are all but deserted at night, despite the Christmas party season being in full swing elsewhere in Britain, with many women refusing to go out after dark until the killer is caught.

Many have compared the killings to those committed by Yorkshire Ripper Peter Sutcliffe, convicted of the deaths of 13 women between 1975 and 1980, and the notorious Jack the Ripper, who murdered five east London prostitutes in 1888.

Detective Chief Superintendent Stewart Gull said the police were making "good progress" but would not be "drawn on the number of people we're interested in" when asked about reports that the police had five suspects.

"Nobody has been spoken to as a suspect at this time," Gull, who is heading the probe, told the daily press conference at Suffolk police headquarters in Martlesham.

However, Jacqui Cheer, Suffolk's assistant chief constable, told BBC radio earlier that police were "looking at 50 to 100 suspects."

She said police were now close to working out the last time the women were seen, which was key to resolving the case.

The victims have been identified as Gemma Adams, 25, Tania Nicol, 19, Anneli Alderton, 24, Paula Clennell, also 24, and Annette Nicholls, 29.

Cause of death has only been established in two cases -- Clennell died of "compression to the neck", while Gull said a post-mortem examination showed Alderton had died from "asphyxiation."

Gull said the police had spoken to the driver of a BMW car -- reported to have picked up Alderton in the week starting December 3 -- and may have to speak to him again.

He has not been eliminated from inquiries, Gull added.

Gull said all the women were found naked, but none showed signs of having been subject to "significant trauma" or "serious sexual assault," fueling speculation that the murderer or murderers might have drugged them.

When asked if the murderer could have been a dealer who spiked heroin sold to the prostitutes, Gull said that police are looking for their drug dealers while awaiting the results of toxicology tests on the victims.

Without ruling out any line of inquiry, he said they are also looking at sex offenders.

The police said that Alderton was three months pregnant, though they said the news was not linked to the investigation.

They also released closed circuit television footage showing Alderton traveling on a train on December 3, apparently the last image of her seen alive.

Her body was found in woodland a week later, but police said a witness had seen it on Thursday and mistaken it for a tailor's dummy.

Gull said he hoped people would call in with other sightings of Alderton based on the footage. He added that if the clothes could be found, they may help police find forensic evidence linked to the killer or killers.

"It's possible we're looking for the same individual, but there may be more involved. We have to keep an open mind," Gull said.

In one of Britain's biggest-ever murder hunts, 350 officers from 31 police forces around the country, including Northern Ireland, have been drafted in to help Suffolk police, Gull said.

Police were still scouring the area for clues.

An AFP photographer saw police entering a caravan hidden in woodland between a highway and a railway, not far from where the bodies of Nicholls and Clennell were found.

They then forced journalists to leave the area.

Today Raymond, who was one of Blunkett's trusted special advisers overseeing prostitution policy for more than three years, calls for the legalisation of prostitution and argues that current policy is 'a disgrace' caused by 'political cowardice' and public indifference.

'The uncomfortable reality is that, while these pitiful girls and women cater to an eternal consumer demand, their lives are being put at greater risk by the lamentable failings of both government and law enforcement,' she says.

Raymond's attack is significant because it is the first account from inside the Home Office of how attempts at liberalisation foundered. She worked closely with ministers in drawing up a consultation paper called 'Paying the Price', which she said was designed to trigger a 'serious debate' about legalised brothels and red-light zones managed by local councils.

It comes as The Observer can reveal that Interpol has now been called into the Suffolk inquiry amid suspicions that the murderer may have fled abroad and that he is thought to have killed with his bare hands.

Yesterday Suffolk police released poignant CCTV images of what is thought to be one of the last sightings of one victim, Anneli Alderton, on a train between Harwich and Colchester on 3 December. Detectives are appealing for information about where Alderton - who was about three months pregnant when she died - went next, including where she left the train.

In the footage, she is seen wearing a black jacket with fur-lined hood, grey top and jeans, with her hair in a ponytail. Seven days later, her naked body was found in woods near Nacton, outside Ipswich.

In her article, Raymond argues that the Ipswich murders illuminate the double standards that govern prostitution, with politicians and senior police officers frightened to wreck their careers by endorsing reforms. She said the consultation paper she helped to write - which proposed, among other options, managed zones patrolled by police, where sex workers could safely take their clients and a register of licensed prostitutes - ran into trouble almost immediately:

'In Whitehall, only a handful of politicians and officials wanted 'Paying the Price' to see the light of day. At the Home Office, the department ultimately responsible, we were divided between those eager to publish - and be damned if necessary - and those wanting the whole issue simply to go away.'

Raymond says there was 'opposition from Number 10, which was terrified of a hostile media response'. The paper eventually surfaced only because Blunkett wanted what he called a 'grown-up debate'. However, a few months later he resigned following allegations over his lover's nanny obtaining a visa and the issue passed to his successor, Charles Clarke.

The result, says Raymond, was a 'watered-down series of proposals' that has still not been implemented.

Blunkett, who has remained loyal to the government from the back benches, insisted yesterday there was no pressure from Downing Street and blamed the previous reticence of many commentators now advocating reform for the fact that it came to nought.

A spokesman for Blunkett said: 'His only regret is that insufficient contributions were forthcoming from so many of those now commenting on the circumstances surrounding the tragic murders in Suffolk and, had they done so at the time, it may have been possible to have had a sensible debate about the issues then.'

When the paper was eventually published in July 2004, it duly triggered hostile comments from media and, more crucially, the police.

After consultation the then minister, Fiona Mactaggart, published proposals in January this year offering only a minor change, allowing a maximum of two prostitutes to work together for safety from a flat. Tolerance zones were ruled out.

Home Office sources last week declined to say when the law might be changed to allow even this limited reform: John Reid, the Home Secretary, is said to be reluctant to debate the issues while the murder hunt continues.

Raymond, however, argues that the 'useless' laws governing prostitution should be scrapped and brothels legalised, with pilot experiments to show whether managed zones can work, too. Liverpool council had been poised to start such a pilot in the wake of the Home Office's initial consultation, but needed a go-ahead from ministers that it did not get.

In a direct appeal, she has urged detectives to take her to the murder scenes so she can try to make contact with the dead working girls.

Mrs Lazarus, 40, who claims to have been able to speak and listen to spirits since she was eight, said: "If I was taken to where the bodies were found I would be able to help police unravel this mystery. Being at the murder scenes, I would get messages which would help me to visualise what the killer looks like.

"If the police and families of these girls want me to help, then I am here. I have worked on many high-profile cases and I would be more than willing to travel to Ipswich to help them out."

Mrs Lazarus' offer comes a year after she helped Norfolk Constabulary to investigate the unsolved murder of 14-year-old schoolgirl Joanna Young who was found dead in a wood just two days before Christmas in 1992.

In 2002, she helped West Midlands Police find the killers of college lecturer Mark Green, after claiming he contacted her from beyond the grave and told her their identity.

Mrs Lazarus said: "I feel this young man in Ipswich wants to be the next Yorkshire Ripper.

"That is what this is boiling down to.

"I don't believe this man is as old as police in Ipswich believe he may be. I think he is a young lad, a hoodie, who, obviously, has no life. I am getting the feeling that he is doing this as part of some kind of religious ritual.

"He must be sitting there rubbing his hands with all the media coverage he's getting.

"I fear there will be more killings but I believe he will make a silly mistake and will be caught by DNA evidence."

Mrs Lazarus is now waiting for a call from detectives, after her husband Peter, who runs one of Wales' leading law firms, telephoned Ipswich Police to offer her services on Wednesday just hours after cops confirmed all five prostitutes were suffocated or strangled and left naked but for their jewellery.

A spokesman for Suffolk Constabulary said yesterday: "We've had a great deal of offers of help.

"We will judge whether Mrs Lazarus can be of use to us as the investigation develops."

Yesterday, detectives were sifting through CCTV footage in a bid to examine the last movements of prostitutes Tania Nicol, 19, Gemma Adams, 25, Anneli Alderton, 24, Paula Clennell, 24, and Annette Nicholls, 29.

The naked body of Miss Adams was found by a member of the public in a brook at Hintlesham, Suffolk on December 2.

Miss Nicol's body was discovered on December 8 near Copdock Mill, Ipswich.

Two days later police found the body of Miss Alderton in woodland on the outskirts of Ipswich. She was three months' pregnant at the time of her death.

And on Tuesday, detectives discovered the bodies of Miss Clennell and Miss Nicholls near the village of Levington, five miles south of Ipswich.

marc.baker@wme.co.uk

"He has been arrested on the suspicion of murdering all five women: Gemma Adams, Tania Nicol, Anneli Alderton, Paula Clennell and Annette Nicholls," Mr Gull said.

"The man is currently in custody at a police station in Suffolk, where he will be questioned about the deaths later today. We will not be naming the police station where the man is being held," he added, refusing to say more or take questions.

The BBC later named the arrested man as Tom Stephens, a 37-year-old supermarket worker who lives in Trimley.

Television footage showed a police cordon around Jubilee Close, a small street of post-war suburban semi-detached houses in the village.

Yesterday's Sunday Mirror carried a lengthy interview with Mr Stephens in which he admitted having used the services of the murdered women and said he was a suspect, but strongly maintained his innocent.

"I am a friend of all the girls," said Mr Stephens, who told the paper he had begun seeing prostitutes 18 months ago, after his eight-year marriage ended. He added: "I don't have any alibis for some of the times.

"From the police profiling it does look like me - white male between 25 and 40, knows the area, works strange hours. The bodies have got close to my house," he told the Sunday Mirror, adding that police had already questioned him four times.

"I know I am innocent and I am completely confident it won't go as far as me being charged," he added.

The arrest follows one of the biggest police operations in recent UK history, which severely stretched the resources of the small Suffolk force. In all, 30 police forces around the country have contributed officers to the 500-strong investigation team.

The hunt for a suspected serial killer was launched when the naked bodies of Ms Nicol, 19, Ms Nicholls, 29, Ms Adams, 25, and Ms Alderton and Ms Clennell, both 24, were found dumped in countryside around Ipswich over a 10-day period.

As yet, police have a cause of death for only two of the victims: Ms Alderton, who was strangled, and Ms Clennell, who died of compression to the neck.

Earlier today, police announced that coroner's inquests into the deaths of Ms Nicol, Ms Alderton, Ms Clennell and Ms Nicholls had been postponed. An inquest into the death of Ms Adams was opened and adjourned last week.

Concerns were first raised publicly on November 7, when Suffolk police said they were "extremely concerned" about the disappearance of Ms Nicol. Just over a week later, they added that they were also worried for the safety of Ms Adams.

On December 2, the body of Ms Adams was found in a brook at Hintlesham, outside Ipswich. Six days later, a body later identified as Ms Nicol's was found two miles downstream.

On December 10, Ms Alderton's body was found in woodland. A day after that, police announced the disappearance of the other two women and urged sex workers in and around Ipswich to stay off the streets.

The naked bodies of Ms Clennell and Ms Nicholls were found within minutes of each on December 12 near the village of Levington.

The massive manhunt saw officers track the last known movements of the dead women. Officers contacted friends, clients and other contacts, and checked the whereabouts of a list of possible suspects that was swiftly narrowed down to about 50 men.

As well as prostitutes, female shoppers and nightclubbers in Ipswich were warned by police to be careful and not walk alone at night.

An appeal for help from the public prompted more than 10,000 calls to police. Mr Gull did not say today what had provided a breakthrough in the operation.

At the weekend, police retraced the movements of Ms Alderton, who was three months pregnant when she was killed, for a fortnight after her disappearance.

She was last seen on CCTV footage taking a train from Harwich to Manningtree on the evening of December 3. From there police believe she then caught a train to Ipswich.

Last night police boarded the same train to talk to passengers who may have seen Ms Alderton on board two weeks ago.

The absence of any signs of a struggle on the women's bodies had led police to believe they may have been incapacitated, perhaps with a large dose of narcotics, before being killed.

At the weekend, Mr Gull said they were no longer looking for a murder weapon, strengthening fears the women were in a state of drug-induced unconsciousness before they were killed.