Agriculture Minister David Heath told the Commons that eight horse carcasses from the UK tested positive for the drug "bute" .
Although Mr Heath told MPs that three of those "may" have entered the human food chain in France, he later confirmed the figure was six.
A total of 206 horse carcasses were tested by the Food Standards Agency.
The EU is urging member states to carry out tens of thousands of tests in the wake of the horsemeat scandal - but who will foot the bill?
Romanians are smarting at accusations that abattoirs there put horsemeat into the food chain.
Poland's deputy chief veterinary officer says his investigation shows the country's meat products are "genuine beef" and alleges fraud.