MMR is offered routinely to all young children in the UK

MMR vaccination rates have been falling since a 1998 research paper claimed the jab was linked to autism and the inflammatory bowel disease.

No link has ever been proven and most experts believe the jab is safe.

The author of the latest study in the British Medical Journal looked at 12 years of data on Crohn's disease.

This provides strong evidence against the hypothesis that MMR vaccine increases the risk of Crohn's disease Researcher Dr Valerie Seagroatt Mumps epidemic grips UK

The findings come as two other studies in the BMJ claim the UK is in the middle of a mumps epidemic because too few children and young adults have been immunised against measles, mumps and rubella.

For the current study, Dr Valerie Seagroatt, a statistician at Oxford University, compared hospital admission rates for Crohn's disease among children and adolescents born either before or after routine MMR immunisation was introduced back in 1988.

'Strong evidence'

She found no increase in Crohn's disease after the introduction of MMR.

"This provides strong evidence against the hypothesis that MMR vaccine increases the risk of Crohn's disease," said Dr Seagroatt.

Some parents have opted to protect their children against the three diseases using single vaccines, as used to be done before MMR was introduced.

But Dr Seagroatt said: "MMR vaccine is no less safe in this respect than the single measles vaccine."

A spokeswoman for the Department of Health said: "It has already been established clearly that measles vaccine does not cause Crohn's disease, in both epidemiological and virological studies, and this study confirms that MMR vaccine does not cause Crohn's disease.

"MMR remains the safest form of protection against measles, mumps and rubella."

Dr Satish Keshav, from the Royal Free Hospital, London, and spokesman for the National Association for Colitis and Crohn's Disease, said: "This is reassuring news for parents.