The British Veterinary Association has said that unregulated horsemeat entering the food chain carries an increased risk from a drug commonly used on horses.
After new reports that horsemeat has entered the food chain and is being sold as beef, Peter Jones, President of the BVA, said:
"These incidents are understandably causing concern about the integrity of the food chain and so it is vital that the FSA and Defra carry out their investigations as quickly as possible.
"Consumers must be able to have confidence in the provenance of their food.
"We are pleased to see that the testing of beef products has been stepped up and that Defra has announced that all horses slaughtered for human consumption will be sampled for the presence of phenylbutazone (bute).
"Phenylbutazone is a painkiller and anti-inflammatory that is traditionally used in horses.
"A Maximum Residue Limit (MRL) in meat has not been established for the use of phenylbutazone in food-producing animals because of concerns regarding the toxicity of the drug and its metabolites, which can be harmful to human health over a lifetime exposure.
"A horse passport system was introduced because of a shortage of licensed medicines for horses considered safe for human consumption.
"Any medicine administered to a horse, not having an MRL established, must be entered into the passport by the veterinary surgeon at the time of treatment.
"This enables the use of such medicines whilst preventing the horse from entering the food chain."
Mary Creagh, Labour's Shadow Environment Secretary, has said she has contacted the police to pass on information that she has received concerning UK mainland companies who are potentially involved in the illegal horsemeat trade.
"I hope that this information will enable the police to act speedily to stamp out these criminals who are putting the future of the British food industry at risk,” she said.
Anne McIntosh, chair of the Commons environment, food and rural affairs committee, has questioned the role of the FSA.
"They have still not found one case of contamination and now regrettably the incidents are spiralling out of control,” she said.
"We did ask last week when the FSA gave evidence to us. We were staggered to learn that the initial incident of the Tesco horsemeat burger could actually have gone on for up to or longer than one year."
She said that horsemeat should not be leaving other countries for the UK.
"There should be physical tests and tests of the labelling of these products before they leave France, Poland or Ireland. This clearly has not happened and now all the onus has been put on the final stage, on the retail supplier."
Despite the continuing headlines about horsemeat being found in processed foods, demand for assured, quality beef has remained robust in the wake of on-going revelations about horsemeat.
EBLEX, the organisation for the beef and lamb industry, said anecdotal evidence from retailers suggested there has not been a significant decline in demand and consumers were increasingly looking for assurance marks when buying products.
Mike Whittemore, head of trade marketing for EBLEX, said:
“Anecdotal evidence has also suggested that consumers are increasingly looking for assurance marks such as Red Tractor and the Quality Standard Mark (QSM) when buying beef products. In that respect demand for assured, quality beef clearly remains robust.
“Provenance of products is important and moving forwards independent auditing, which is already a key requirement of both the Red Tractor and Quality Standard Mark (QSM) assurance schemes, will play a key role in ensuring that consumers have confidence in what they are buying.”