Welsh fast food supplier the Burger Manufacturing Company has issued a product recall after three samples of its beef burgers tested positive for horse.

The Food Standards Agency said tests by Powys County Council had found “at least 1%” in the burgers, and more tests were taking place to quantify exactly how much horsemeat they contained.

The burgers would also be tested for phenylbutazone, the veterinary medicine also known as bute, the FSA added.

In a statement, BMC said it had traced back the contamination in its products to Farmbox Meats, the Welsh company that was raided by the FSA last week. Two Farmbox Meats employees were arrested but have since been bailed. Farmbox maintains it has done nothing wrong.

“We pride ourselves on using quality meat from, where possible, locally source suppliers,” BMC said. “Our decision to use Farmbox Meats was to help boost local businesses, and because of our belief in the quality of their meat. It is disappointing that on this occasion the high standards we expect have not been met.”

BMC added it had stopped using Farmbox with immediate effect and would be adding in place “continued DNA testing” on its products to avoid a similar incident in the future.

BMC describes itself as a “major supplier to the fast food market” offering both halal and non-halal products. Its sister company, Sparks Catering Butchers, is a large wholesale supplier of burgers in the South-East.

The withdrawal of the BMC products comes as the FSA prepares to publish the next wave of industry test results on processed beef products tomorrow. Last Friday, the results for the first 2,501 samples were announced, with 29 samples testing positive for more than 1% horse.