One in five poultry producers which abandoned the use of antibiotic growth promoters to make chickens grow faster are using them again, it was revealed today.

Environment Secretary Margaret Beckett has asked officials to examine the legality of a move by the Assured Chicken Production scheme, which has allowed the reintroduction of antibiotic growth promoters under controlled conditions.

The ACP covers an estimated 90% of the 15 million UK-produced chickens eaten every week and was set up in 2000 to set standards with the promise that antibiotic growth promoters would not be permitted.

The special permission to reintroduce the growth promoters was granted in March last year for 12 months and has been extended for further period until March 2004.

Drugs are 'legal'

Professor Sir Colin Spedding, chairman of Assured Chicken Production, said the drugs had been allowed after complaints about diarrhoea in chickens which caused "hock burn".

He said the move was legal under EU law which allows the use of the growth promoters until 2006.

He said: "We had a lot of complaints, not only from producers but mainly from veterinarians and also from retailers like Tesco, who said that as a result of our ban the welfare of birds was suffering.

"We decided that since the growth promoters we use are perfectly legal as growth promoters which is how we are using them, and they do no harm to anybody because they are not the sort that cause resistance relevant to humans, that we would have a trial period."

Protest from Soil Association

But The Soil Association, the campaigning group and certification organisation for organic food and farming, said that under EU law the move was illegal as antibiotic growth promoters cannot be used to control disease since they have never been evaluated for safety as veterinary medicines.

The association has said it is concerned that the overuse of drugs in animals will endanger human health by increasing the speeds at which bacteria develop resistance to antibiotics.

What the supermarkets say

A spokesman for Tesco said around half of its suppliers were now using antibiotic growth promoters - known in the industry as anti microbial digestive enhancers (ADES) to help prevent digestive disorders in chickens.

Tesco was seeking to phase out the use of ADEs in all its chickens, he said.

"Safety is our top priority. There are no human health risks associated with the use of ADEs. These drugs pass through the gut wall of the chicken and are therefore never detectable in meat," he said.

A spokeswoman for Safeway said chickens on sale in the supermarket had not been reared with antibiotic growth promoters.

A spokesman for the Grampian Country Food Group, which produces 200 million broilers a year, representing around a quarter of the of the home-grown chicken supply, said: "It still remains the policy of the Grampian Country Food group not to use any antibiotic growth promoters within any of our chicken growing operations."

A spokeswoman for Sainsbury's said: "We don't believe it's necessary for the welfare of chickens to use antibiotic growth promoters.

"Although permissible under the Assured Chicken Production standard, we can confirm that our suppliers make no use of them in all our UK-produced broiler chickens."

A spokesman for the Co-op supermarket group said 99% of its whole chickens on sale were their own brand and the Co-op did not allow producers to use antibiotic growth promoters.

The rest were organic chickens which did not use antibiotic growth promoters.