The expert whose research shows no link between MMR and autism says he hopes his findings will put an end to the controversy over the vaccine.

The latest research from the Royal Free Hospital comes as Prime Minister Tony Blair gave another hint that his son Leo has had the jab.

It has been suggested the MMR had caused a particular form of autism - known as new variant autism - in which children deteriorate over time and suffer bowel disorders.

However, the Royal Free scientists found no evidence of such a link.

The research, published on the British Medical Journal's website, looked at case records for almost 500 children with autism born between 1979 and 1998.

It found the proportion of children with developmental problems or bowel disorders did not change significantly over that time.

The measles, mumps and rubella triple jab was introduced 1988.

The researchers say if there was an association between MMR and new variant autism, there would have been an increase in cases after that date.

Autism was just as likely among children who did not receive MMR, or to have surfaced in children before they were vaccinated.

This is the third time the researchers have conducted a study of this type - on each occasion for a longer period. Each time, the results have been the same.

Professor Brent Taylor of the Royal Free who led the research told BBC News Online: "There is no evidence of a new variant form, no evidence."

He added that there was "no relation whatsoever" between MMR and autism, and a "huge amount of good evidence that there's no relation".

Professor Taylor added children were being put at risk of measles, mumps and rubella by not having the MMR jab.

He added: "I hope that this is the end of the argument."

Ongoing controversy

The past week has seen a new wave of controversy over the safety of the MMR jab, with many parents and campaign groups are calling for the measles vaccine to be available separately.

Government experts have said this would inevitably put more children at risk.

In statement posted on the 10 Downing Street website, Tony Blair said: ""It is the responsibility of all of us, as parents, to ensure our children's health.

"Against measles, mumps and rubella, the combined MMR vaccine is the best way of doing that."

Dr Peter Dukes of the Medical Research Council, which carried out a review of autism research including looking at whether there was a link with MMR, told BBC Radio 4's Today programme: "The evidence shows there's no link between MMR and autism.

"What people feel about it is probably another matter."

Jackie Fletcher from Jabs, the support group for parents who believe their children have been damaged by the vaccine told : "What concerns us is that we have a huge body of children 1,600, believed to have been affected by the MMR and they have not been investigated.

But Judith Barnard, director of policy and public affairs for the National Autistic Society said: "The experts themselves came to the conclusion that there couldn't exclude the possibility of a susceptible sub-group that could be affected by the MMR.

"The real question is how to identify that."

Ms Barnard said some children developed serious bowel conditions and severe regressive autism, when they had previously been healthy.

"I think its high time we stopped playing this ping-pong game and actually committed to doing this research around this group to find out what they have in common, what has caused this condition in these children."