Operation Ore, the police inquiry which plans to arrest a further 7000 men across the UK, in addition to Who guitarist Pete Townshend, for buying child pornography online is set to end in disaster with many suspects walking free.

Detective Chief Inspector Bob McLachlan, former head of Scotland Yard's paedophile unit, told the Sunday Herald that the lack of urgency in making arrests will lead to suspects destroying evidence of downloading child pornography before they are arrested.

The Sunday Herald has also had confirmed by a very senior source in British intelligence that at least one high-profile former Labour Cabinet minister is among Operation Ore suspects. The Sunday Herald has been given the politician's name but, for legal reasons, can not identify the person.

There are still unconfirmed rumours that another senior Labour politician is among the suspects. The intelligence officer said that a "rolling" Cabinet committee had been set up to work out how to deal with the potentially ruinous fall-out for both Tony Blair and the government if arrests occur.

Since the September 2002 Operation Ore arrest of Detective Constable Brian Stevens, a key officer in the inquiry into the murders of Holly Wells and Jessica Chapman, the public have been aware that wanted suspects had downloaded child pornography from a US website called Landslide.

McLachlan, who was one of the main officers on Operation Ore before his retirement last year, said: "Sufficient warnings have been given that if people haven't got rid of their computers then they are either stupid, don't believe they'll be arrested or are so obsessive about their collections that they can't destroy it. As time goes on, the chances of successful prosecutions will diminish with speed as the information out there must impact on the offenders."

With only 1200 men arrested so far, McLachlan says that claims by police chiefs and the government that they were prioritising paedophile crime were "smoke and mirrors". Paedophilia is still not a priority on the Home Office's National Policing Plan for 2003-06. McLachlan claimed that before he left Scotland Yard his team were under-staffed, over-worked, under-funded and reduced to using free software from computer magazines.

There are around one million images of an estimated 20,000 individual children being abused online. Some police seizures involve hauls of more that 180,000 images. Last year, images of 13,000 new children were uncovered. Only 175 child victims have been identified worldwide.

Police have also revealed that images of Fred West abusing one of his children are among child pornography available for downloading from the internet. It is unclear whether the child was West's murdered daughter Heather.

Peter Robbins, the chief executive of the Internet Watch Foundation, which works with the police, government and internet service providers, in tackling paedophilia online, says software is in development which could remove child pornography from the net forever. The software should be ready in two years.

Police say that the list of rich and famous Operation Ore suspects would fill newspaper front pages for an entire year.