French police have arrested 21 people in raids connected to horsemeat used in lab tests which was sold as fit for human consumption.
Gendarmes, with food safety and veterinary investigators, carried out raids in 11 regions in southern France before dawn.
One official said the animals had been used in laboratories - including that of drugmaker Sanofi-Pasteur - and then, instead of being destroyed, ended up in the food chain.
Sanofi said that the horses were used to create antibodies against rabies and tetanus among others. The company, which said it cooperated in the investigation, said it has resold about 200 horses in the past three years to vet schools, individuals and professionals.
The company said the lab uses horses for about three years before re-selling them, tagged and certified. It said it does not carry out testing on the animals.
Benoit Hamon, France's consumer affairs minister, told RTL radio that it was a question of food safety, rather than simple fraud.
"These were horses that should have ended up at the slaughterhouse, and instead they ended up at the butcher," he said.
Hamon drew a sharp distinction between the raids and a scandal earlier this year in which inexpensive - but edible - horse meat was passed off as beef and sold in supermarkets and restaurants around Europe.
"There are horses that should end up neither on your plate nor at the butcher, and that's the work of this investigation" he said.