Cadbury and Mars have been accused of "breaking promises" on their use of six artificial colours deemed in the UK to increase hyperactivity in some children.

Not all Cadbury and Mars products on sale in the UK contain the colours, which include Quinoline Yellow and Carmoisine - also known as E104 and E122 - and which have been linked to hyperactivity.

However, campaign group The Food Commission yesterday (19 March) slammed the confectionery giants for continuing to use them in selected lines despite earlier promises to remove them.

The Food Commission criticised Cadbury for continuing to use the six additives in products like Cadbury's Creme Egg despite pledging in 2007 to discontinue their use.

The campaigners also rebuked Mars for continuing to use two of the colours in Starburst Choozers and three of the six in Mars Revels - despite a similar 2007 pledge.

Action on Additives co-ordinator Anna Glayzer said: "To make these pledges at times of high media attention and then quietly neglect to honour them is simply cynical PR opportunism. It is highly irresponsible behaviour from major multinational confectioners, especially when many other companies have reformulated."

Last month, the UK's Food Standards Agency threw its weight behind a voluntary ban on the six food colours.

The move came after researchers at the University of Southampton published the results of a study concluding that certain artificial food colours and additives exacerbate hyperactive behaviour in children.

The FSA has also published a list of companies complying with the voluntary ban on its site. However, the Food Commission said the move did not go far enough.

"At the moment, FSA efforts to enforce the voluntary ban consist of three very short lists hosted on a difficult to find area of the agency's website," Glayzer said. "It is of little help to parents and it fails to give an accurate picture of the UK market. A mandatory ban would be simple, effective and would take the burden off the parents."

Officials at Cadbury, Mars and the FSA could not be reached for immediate comment.