"There are two victims in this affair: Findus and the consumer," Findus France said in a statement.

The British arm of Findus said it is considering legal action against suppliers as well. Early results of an internal investigation "strongly suggest" the horse meat contamination of a beef lasagna product "was not accidental," the company said.

Tests showed up to 100% horse meat

Aldi said tests on random samples demonstrated that the withdrawn products contained between 30% and 100% horse meat.

"This is completely unacceptable and like other affected companies, we feel angry and let down by our supplier. If the label says beef, our customers expect it to be beef."

Samples of the affected Findus lasagna contained between 60% and 100% horse meat, according to UK and Irish food safety inspectors.

In January, the Food Safety Authority of Ireland found that 10 out of 27 hamburger products it analyzed in a study contained horse DNA, while 23 of them -- or 85% -- tested positive for pig DNA.

In nine out of the 10 burger samples, the horse DNA was found at very low levels, the inspectors said. But in one sample from Tesco, Britain's largest retailer, the horse meat accounted for about 29% of the burger.

Tesco apologized and vowed to make sure it never happens again.

Irish officials blamed ingredients from Poland.

Concerns about a veterinary drug

While horse meat is not itself a food safety hazard, food inspectors are concerned it may contain the veterinary drug phenylbutazone, or "bute," commonly used to treat horses.

Meat from animals treated with phenylbutazone may pose a risk to human health and is not allowed to enter the food chain as it may pose a risk to human health.

Findus has been ordered to test the lasagna withdrawn from shelves in the United Kingdom for the drug's presence.

The revelations have revolted many meat eaters in the United Kingdom, where horse meat is generally considered taboo, although it is commonly eaten in neighboring France, as well as countries including China, Russia, Kazakhstan and Italy.

The discovery of pig DNA in beef products is of particular concern to Jews and Muslims, whose dietary laws forbid the consumption of pork products. Jewish dietary laws also ban the eating of horse meat.

The UK Justice Ministry confirmed last week that a number of meat pies and similar items supplied to prisons in England and Wales were labeled and served as halal -- prepared in compliance with Islamic dietary law -- but contained traces of pork DNA, the Food Standards Agency said.

Horse meat is not commonly eaten in the United States, but the country does export it to Canada and Mexico. Congress passed a bill in November 2011 that lifted a 5-year-old ban on the slaughter of horses for meat in the United States.