According to a new but as yet unpublished study, the number of children in Britain with autism is far higher than previously thought.
Some of Britain's top experts say new evidence suggests that as many as 1 in 58 children may have some form of the condition compared to previous estimates of about 1 in 100.
Autism Spectrum Disorders are a lifelong disability with no known cure and range from severe cases of "classic" autism where a child is often unable to speak to much milder cases and includes Asperger's syndrome.
Sufferers have problems socialising and communicating and many have obsessive behaviours which impede learning and development, with victims becoming isolated and unable to function in a fulfilling manner in society.
The study was conducted by researchers at Cambridge University's Autism Research Centre, who examined 12,000 children at primary schools in Cambridgeshire between 2001 and 2004.
Two of the academics who are considered to be leaders in their field have apparently suggested that the surprisingly high figure may be linked to the use of the controversial MMR vaccine.
But that opinion has been rejected by the rest of the team, including its leader, the acclaimed autism expert, Professor Simon Baron-Cohen.
The researchers found that 1 in 58 children has either autism or a related autistic spectrum disorder which equates to a nationwide figure of as many as 210,000 children under 16, a figure well above the existing estimate of 1 in 100, which organisations such as the National Autistic Society believe to be the case.
Some experts who previously explained the rise in autism as the result of better diagnosis and a broader definition of the condition now believe the upward trend revealed by studies such as this indicates that there has been a real rise in the numbers of children who are affected by it.
The new research however is purely statistical and does not examine possible explanations for the rise.
The two authors Dr. Fiona Scott and Dr. Carol Stott who believe that the MMR jab, which babies receive at 12 to 15 months, might be partly to blame, both say it could be a factor in only small numbers of children.
Professor Baron-Cohen, director of the centre who is the country's foremost authority on the condition, disputes this claim and says he does not believe there is any link between the three-in-one vaccination and autism.
The professor cites genetic and environmental factors, better recognition of the condition, and children's exposure to hormones in the womb, especially testosterone, as more likely to be the cause.
He says the evidence does not support the idea that the MMR causes autism.
The MMR triple shot has been enmeshed in controversy since 1998 when Dr. Andrew Wakefield, a gastroenterologist at the Royal Free Hospital in North London declared it was unsafe and might cause autism and inflammatory bowel disease in children.