LONDON - A link between the rise in autism and the MMR jab is rejected by a new study which claims to have found "compelling evidence" that the triple vaccine is safe.

The reported surge in childhood autism cases is not real and is mainly due to better diagnosis, according to the latest study. Scientists also found no evidence of a new type of MMR-triggered autism.

They suggested that parents who blame the jab for triggering autism in their children may have been influenced by media coverage of the controversy.

The researchers found that the number of parents who dated the start of their child's autism back to their MMR vaccination only began to rise after the publication of controversial research which first suggested a link.

The new study, published in the journal Archives of Disease in Childhood, was carried out by Professor Brent Taylor of the Royal Free Hospital in London.

It was another Royal Free scientist, Dr Andrew Wakefield, who first published research in 1998 which claimed MMR had triggered a new variant of autism in a small group of susceptible children.

The study caused uptake of MMR in Britain to plummet, which in turn led to a resurgence of measles and mumps outbreaks in schools.

More than 1,500 families are now bringing legal action against the vaccine manufactures, claiming their children have been damaged.

Dr Wakefield said his study led him being hounded out of the Royal Free. He now works in America.

The doctor and his supporters say their claims are backed by studies which have suggested a sevenfold increase in autism cases in the 10 years since MMR was introduced in 1988.

Professor Taylor and his team studied medical records for five areas of north London between 1979 and 1998.

They found that there was an apparent rise in autism cases until 1992, since when prevalence has plateaued.

More importantly, the age at which children were diagnosed had fallen substantially over time. Professor Taylor said: "This levelling off, together with the reducing age at diagnosis, suggests that the earlier recorded rise in prevalence was not a real increase but was likely due to factors such as increased recognition, a greater willingness on the part of educationalists and families to accept the diagnosis, and better recording systems."

The team also found that before the Wakefield research was published in 1998, parents of autistic children were more likely to date the start of problems back to events such as domestic stress or a viral illness.

After the research received worldwide publicity, the most likely trigger claimed by parents was vaccination, and in particular, MMR.

Professor Taylor concluded: "The claims that MMR vaccination is involved in the initiation of autism ... are not supported by any credible scientific evidence, while there is compelling and increasing evidence showing no association."

Stuart Notholt, director of policy at the National Autistic Society, said: "The rise in reported cases of autism has been reported in other papers ... but whether there has been a true increase is not known.

"It might be expected that with growing familiarity with autistic spectrum disorders, prevalence figures would begin to level out."

The autistic society has called for more research into autism rates.

Meanwhile, it has remained neutral about whether there is a link between the condition and MMR.

MMR vaccine

* MMR stands for measles, mumps and rubella - a vaccine used in New Zealand and Britain.

* Five years ago scare stories about an alleged link with autism caused vaccinations to plummet in Britain.

* New research confirms the vaccine is safe.

- INDEPENDENT