Britain's Food Standards Agency ordered tests on all processed beef products after two frozen beef lasagnas were found to contain horse meat.
The food company Findus said 11 of 18 of their ready-to-eat meals, advertised as containing 100 percent beef, were actually 60-80 percent horse meat, the newspaper The Daily Telegraph reported Friday, adding the company has withdrawn 180,000 lasagnas from sale for further testing.
In a statement Friday FSA said the investigation "points to either gross negligence or deliberate contamination in the food chain."
"I have to say that the two cases of gross contamination that we see here indicate it is highly likely there has been criminal and fraudulent activity involved," said Catherine Brown, FSA chief executive.
The foods are being tested for a painkiller, given to horses, which can cause serious blood disorders, the newspaper said.
Findus said a French firm, Comigel, has been supplying meat for its lasagnas for more than two years.