Asda has withdrawn four frozen burger lines as a precaution, after frozen meat detained in a cold store in Northern Ireland was found to contain 80% horse DNA.

The cold store in question is owned by Freeza Meats, which also supplies the four burgers to Asda. However, the products containing horse DNA are not any of Freeza’s own products but were stored by Freeza on behalf of a meat trader from County Monaghan, who sourced the contaminated meat from Poland.

Freeza said all its own products had come back negative for horse DNA, and stressed the meat it had stored for the other trader had been kept in a separated area of its cold store. The company’s account has been backed by Newry & Mourne district council, whose environmental health department said “DNA test on samples of burgers made at Freeza Meats were found to be free from non-beef DNA”.

Asda said its own tests on Freeza’s products had also come back free of any trace of horse meat, but had decided to withdraw the four burger lines any way to be on the safe side. “Although all the science says there is no trace of horse in our burgers produced by Freeza Meats, we can’t and won’t take any chance when it comes to the authenticity of ingredients in our products,” a spokeswoman said.

“As a precaution, we have taken all four burger products off sale produced in that factory, and have instructed Freeza Meats to segregate and hold any frozen burgers currently in production or in their supply chain destined for Asda,” she added. “These four products will remain withdrawn from sale until further notice.”

Asda’s withdrawal of the four Freeza-supplied frozen burgers comes after the retailer withdrew a number of burgers made by ABP Food Group’s Silvercrest plant as a precaution in January. Asda subsequently confirmed it had found traces of horse DNA in a four product samples.

Freeza was not immediately available to comment on the Asda withdrawal.