The Food Standards Agency also says it has started its own survey of meat products in UK supermarkets, in association with local authorities.
It will do tests to show whether they contain horse or pig DNA, and if so, how much.
The horsemeat scandal demonstrates how long and complicated the food chain we all depend on is. Regulating our food supply is expensive.
Some of the best, and worst, jokes and gags from Twitter users discussing the discovery of horse DNA in some supermarket beef burgers.
We've seen the jokes on Twitter but the discovery of horse and pig DNA in beefburgers poses a serious question; where did it come from?