Fresh fears over a possible link between the measles, mumps and rubella (MMR) vaccine and autism have been raised after a new study found that almost double the number of children could have the condition than previously thought.

Researchers at Cambridge University's Autism Research Centre (ARC) have estimated that one in 58 children suffer from some form of the disorder, compared to previous estimates of about one in 100.

The figures mean up to 210,000 children under 16 across the UK could have some form of autism, the unpublished research by the ARC found.

Two of the seven experts who took part in the study have now privately voiced concerns that the controversial MMR vaccine may be a factor in the emergence of autism among some children.

Dr Fiona Scott and Dr Carol Stott have reportedly said they think the jab, given to children between 12 and 15 months, could be responsible for growing numbers of children apparently exhibiting symptoms of the disorder. However, the other five, including team leader Professor Simon Baron-Cohen, rejected their view.

Autism is the term given to a wide range of development disorders that affects an individual's ability to understand the world and communicate with others. It covers a "spectrum" ranging from severe cases of "classic" autism - which often renders a child unable to speak - to much milder Asperger's syndrome, which can affect a person's ability to socialise.

Until the early 1990s experts believed that only four or five people in 10,000 suffered from the condition. Since then studies have shown autism is much more common, with experts generally agreeing on the one in 100 figure.

Academics agree much of the apparent increase can be explained by the fact that more people are now aware of what autism is. But there is still a heated debate about whether or not autism is actually becoming more common in children.

Last year a study reported in the medical journal The Lancet put forward an estimate that one in 86 children suffered from some form of autism. The ARC's paper, based on a study of 12,000 primary school children in Cambridgeshire between 2001 and 2004, raises the estimate significantly.

The results of the study, which was purely statistical and did not examine the possible medical causes of autism, so worried Professor Baron-Cohen that he contacted health officials in Cambridgeshire.

However, the professor - who is a first cousin of the comedian Sasha Baron-Cohen - stressed he did not believe the MMR vaccine was behind the apparent increase.

Professor Baron-Cohen said: "As for MMR, at this point one can conclude that evidence does not support the idea that the MMR causes autism."

He said he believed a better understanding of autism and environmental factors such as exposure to chemicals and hormones were more likely to be behind the recorded increase. Nonetheless, the research is bound to spark renewed doubts among concerned parents about the safety of the triple vaccine.

The percentage of children being given the jab fell dramatically after doubts were raised over its safety by Dr Andrew Wakefield, a gastroenterologist at the Royal Free Hospital in London. Vaccination rates have only just started to recover.

In 1998 Dr Wakefield co-authored a paper published in The Lancet which looked at bowel disease in 12 children with autism, and suggested a possible link with the MMR vaccine. Later he gave a press conference calling the safety of the vaccine into question and recommending children should be given the three inoculations separately.

Ten of the 13 academics who contributed towards the paper soon retracted its conclusions, but Dr Wakefield and two others have stuck by the 'interpretation'. Dr Wakefield is due before a General Medical Council hearing next week to answer a number of charges in relation to the 1998 study.

The new report has also triggered calls for the Government to do more to further the understanding of autism and help those with it.

Benet Middleton (OK), director of communications at the National Autistic Society, said: "There is an urgent need for a clear Government strategy for responding to autism.

"We need to have an accurate picture of how many people have autism, we need adequate services in place to support people with autism and we need those working with people with autism to have the right training.

"Current provision for those with the disability is deeply inadequate given the scale of the need. Autism is a lifelong disability and when an individual's needs are not met the long term consequences both financially and for the individual's well being are profound."

Ivan Corea, head of the Autism Awareness Campaign UK, said many autistic people were at the mercy of a "postcode lottery".

She said: "We are urging Gordon Brown to provide a world class education for all children with autism and Asperger's Syndrome, to provide new specialist autism schools, even Special Needs Academies and autism units equipped with sensory rooms in mainstream primary and secondary schools."

A spokesman for the Health Protection Agency (HPA) today stressed the MMR vaccine was safe.

She said: "We have not seen this report, which has not been published yet and has not been peer reviewed, so we cannot comment on it. Every test that has tried to find a link between MMR and autism has not found one. MMR is a safe vaccine."

Comment: Except, obviously, the Wakefield report, the authors of which were threatened into retracting its results. Wakefield himself, though, refused to be bullied into submission.