France found more cases of illegal horsemeat in beef products than any other EU country, early results of DNA tests ordered in the wake of the scandal showed, with more than 1 in every 8 samples testing positive.
The European Commission is due to announce the results of the tests later on Tuesday, but EU sources said a progress report from the EU's executive dated April 9 showed that of 353 tests carried out in France, 47 tested positive for horse DNA.
Europe's horsemeat scandal has damaged confidence in parts of the continent's food industry, hitting sales of processed ready-meals and boosting demand for organic produce.
The progress report only included complete data for 11 EU countries. Greece had the second-highest level of positive results with 288 tests yielding 36 positive results - a rate of 12.5 percent. Germany found horse DNA in 29 samples out of 867.
In Britain, where horsemeat has already been found in burgers and other products sold by retailers including Tesco , 150 official tests carried out as part of the EU-funded programme returned no positive results for horsemeat.
But one senior EU official said Britain had recorded the most positive results for the potentially harmful veterinary drug phenylbutazone - known as bute - as part of a second set of EU-wide tests on horsemeat destined for human consumption.
"The bute is now really concentrated in the UK, but mainly because the UK has tested every horse slaughtered since February, so they have done a huge number of tests - more than 800," said the source, who spoke on condition of anonymity.