The latest study, conducted for the Food Standards Agency (FSA), is thought to support findings first made seven years ago that linked the additives to behavioural problems such as temper tantrums, poor concentration, hyperactivity and allergic reactions.

A team at the University of Southampton tested the additives tartrazine (E102), ponceau 4R (E124), sunset yellow (E110), carmoisine (E122), quinoline yellow (E104) and allura red AC (E129) on both 3 year olds and 8-9 year olds.

All the additives tested in the study are approved for use in the EU and are safe but some of the colours are banned in Scandinavian countries and the US.

The FSA said it would not issue formal recommendations until the findings were published, but independent experts said parents should avoid foodstuffs containing the additives.