Two other scientists behind the Danish reports, Mads Melbye of Statens Serum Institut and Kreesten Meldgaard Madsen of Aarhus University Hospital, told the Philadelphia Enquirer newspaper that Thorsen was only one researcher in the groups behind the studies and had little or no influence on the ultimate conclusions.

Denmark ceased to use mercury-based substances in its vaccines in 1992. However, autism cases continue to rise here as well, although the percentage continues to be far under that of children in the US.

Many experts also say that the increase can be partly explained by the fact that more doctors are now recognising the disorder.