Supermarket chain Asda said on Tuesday that it was recalling its range of budget corned beef after low levels of the veterinary pain killer phenylbutazone – known as bute – were detected.

The Food Standards Agency said the retailer had confirmed that the drug was detected in 340g tins of Asda Smart Price Corned Beef that had previously been found to contain traces of horsemeat.

The discovery is the first confirmation that products containing the drug have been sold in the UK after concerns were raised in the wake of the horsemeat scandal. Previously, eight horse carcasses slaughtered in the UK for consumption tested positive for bute, but the meat was exported.

Bute is banned from the human food chain as it could pose a health risk. But the FSA said the risk to people who had eaten products containing contaminated horse meat was low.

Asda said the affected product, which had been withdrawn from sale in March when the horsemeat was detected, contained "very low levels of bute", registering four parts per billion. It urged customers to return tins to their nearest store: "Although there is a very low health risk, we are recalling this product. This simply means that we ask anyone who has tinned Smart Price Corned Beef (340g) in their cupboards at home to bring it back into store for a full refund."

The retailer said it was also withdrawing 340g tins of its Chosen By You corned beef as a precaution as they were made in the same factory as the contaminated products.

"We want you to have complete confidence in the food you buy at Asda and we are happy to refund any product you're not 100% happy with," it said. The FSA said no other Asda products were thought to be affected.

Asda claimed to have taken "an extremely cautious approach since the very beginning" and had carried out more than 700 tests, "moving swiftly to remove any products" when they had any concerns. "The FSA has reassured us that the quantities we've found pose a low risk to human health."

The FSA's chief medical officer, Dame Sally Davies, said the levels of contamination would be too low to have any significant impact on anyone who had consumed the affected meat. "Phenylbutazone, known as bute, is a commonly used medicine in horses. It is also prescribed to some patients who are suffering from a severe form of arthritis," she said.

The levels of bute previously found in horse carcasses meant a person would have to eat up to 600 burgers, containing 100% horsemeat, every day to come close to consuming a human's daily dose of the drug, she said."In patients who have been taking phenylbutazone as a medicine, there can be serious side effects but these are rare. It is extremely unlikely that anyone who has eaten horsemeat containing bute will experience one of these side effects."

Horse carcasses in the UK are required to have a negative bute test before they can enter the food chain but the Guardian discovered in February that two carcasses which tested positive for bute in 2012 were not reported to the FSA for up to seven months.

Asda's announcement came as a new study revealed that the government appeared to have averted a crisis of confidence in the meat industry by telling consumers the horsemeat scandal posed no health risk. A poll of more than 8,000 people found that few people were changing their shopping habits because of the scandal.