The voluntary ban in the UK on the use of six food colourings linked to hyperactivity in children is working, the country's food watchdog has insisted.

The Food Standards Agency today (20 March) defended its stance after claims from a campaign group that a mandatory ban would be more effective in getting food makers to change recipes.

The Food Commission has criticised the FSA's voluntary ban, which came in after UK researchers published a study that concluded there was link between six colours and hyperactivity in kids.

"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," Action on Additive co-ordinator Anna 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."

However, the FSA said food suppliers were changing how they made products containing the colours.

"We know that industry is responding to calls to remove these additives, many supermarkets have completely removed them from their own label brand products," the FSA told just-food.

The Food Commission has also slammed Cadbury and Mars for continuing to use the artificial colours in selected lines despite earlier promises to remove them.

However, Cadbury claimed the campaign group was "wrong" and said the company's pledge had covered sweets and not chocolate.

"We achieved our goal of removing all artificial colours from our sweets range by the end of last year as we promised," A Cadbury spokesman told just-food.

"We have completed testing on the remaining chocolate brands, to ensure consumers enjoy the same quality, and these will also be switched over in the coming months."

Mars, meanwhile, said it had removed the colours from Starburst Chews and Skittles and would look to strip the additives from Minstrels and Revels by the end of the year.

The company said it had had "small technical difficulties" with reformulating its Starburst Choozers line.

"On 6 March, we started to manufacture Starburst Choozers free from these colours and anticipate these will start to appear on shelves in May," Mars told just-food.

The FSA said suppliers had found it "difficult" to find alternative colours and that consumers who wanted their children to avoid the additives could check a product label or the agency's site.

"The removal of these colours is voluntary, not compulsory, but consumers who don't want their children to eat these colours can vote with their feet - you just need to check the label," the FSA said. "Our website list helps people identify which products ranges and brands are completely free from the colours."

The FSA added: "New labelling laws will come into force from July 2010 that require all food containing these colours to state 'may have an adverse effect on activity and attention in children'."