The supermarket giant said it had pulled from its shelves the 600g packs of Tesco Simply Roast Meatloaf made between October last year and January at Eurostock in Craigavon.
Tesco said it was the fourth of its products to test positive for horsemeat contamination.
Tim J Smith, the chain’s group technical director, said: “Tests on 15 other lines from the same manufacturing site were clear of horsemeat.”
He added: “Our investigation to thoroughly understand the source of the contamination has started, and we will complete our investigation before deciding whether to continue using the supplier.
“We are very sorry that we have had a further product which has failed to meet the high standards we and our customers expect.”