A website offering parents advice on childhood immunisation has been ordered to remove information about the MMR vaccine after renewing claims that it could be linked to autism.
Babyjabs.co.uk said the vaccine "could be causing autism in up to 10% of autistic children in the UK".
It also said: "Most experts now agree that the large rise (in autism) has been caused partly by increased diagnosis, but also by a real increase in the number of children with autism."
A further claim said the vaccine-strain measles virus has been found in the gut and brain of some autistic children, which supports many parents' belief that the MMR vaccine caused autism in their children.
One person complained that the claims are misleading and unsubstantiated.
Defending the claims, Babyjabs referred to one study in particular from 2002, which it considered to be one of the strongest pieces of evidence that the MMR vaccine does not cause autism but which it claimed includes the lead author's conclusion: "We cannot rule out the existence of a susceptible subgroup with an increased risk of autism if vaccinated."
It also said The Truth About Vaccines, a book written by Babyjabs medical director Dr Richard Halvorsen, stated: "If one in 800 MMR vaccinations triggered an autistic disorder, this would result in around 1,200 children a year in the UK being made autistic by the bundling of the vaccines. This is probably the worst case scenario."
Dr Halvorsen added that "research, including large population studies, has since shown that the MMR is not causing the large majority of autism, but has been unable to exclude the possibility that it is causing autism in a small number of susceptible children".
Upholding the complaint, the Advertising Standards Authority (ASA) noted that the website makes clear that the original allegations of a link between the MMR vaccine and autism by Andrew Wakefield was "strongly rejected" by government and the medical establishment".
But it said consumers are likely to infer from the website's claims that the vaccine might have played a role in the "increase" in the number of children with autism.
The ASA said: "We understood that the position held by the World Health Organisation and the Department of Health was that no evidence existed of a causal association between the MMR vaccine and autism or autistic disorders, and that the Cochrane review, looking at the general evidence available, could find no significant association between MMR immunisation and autism.
"We noted that the evidence provided by the advertiser included studies and an article which looked at the increased prevalence of autism, but did not include evidence that any increase was due to the MMR vaccine."
It ruled that the claims must not appear again in their current form.