The Food Standards Agency has said it will continue testing products "until there's nothing left to find" after the veterinary painkilling drug phenylbutazone - or bute - was found in Asda Smart Price Corned Beef.
The agency's director of operations Andrew Rhodes said customers should not eat the corned beef but added anyone who does is very unlikely to fall ill.
He advised customers to return the product to the supermarket to receive a full refund.
More top news
Some of the children at the Royal Free Hospital in London were less than impressed with their visit from Alex Oxlade-Chamberlain.
How closely have you been paying attention to the news this week? Test your memory with our Friday quiz.
The FBI said three key elements of the Sony Pictures cyber attack led them to identify the administration in Pyongyang as the culprits.