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
Ministers are ready to reduce the waiting time for Universal Credit payments following an outcry from Tory MPs, it has been suggested.
Storm Brian will bring strong or very strong winds across southern and western parts of the UK
The spanish PM said he wants the country's senate to give him direct power to dissolve the Catalan government and call an election.