French police made 21 arrests Monday as part of an investigation into claims that meat from horses used to produce anti-rabies and other serums got into the food chain.
The arrests were made at various locations in the south of France following a tip-off that hundreds of horses, including some that had been owned by pharmaceutical giant Sanofi, were sold to abattoirs after their veterinary papers were falsified, a police source told AFP.
More than 100 officers were involved in raids at several Sanofi offices and at various abattoirs, including one in Gerona in northern Spain.
Among those arrested were at least three vets and several meat dealers, including one based in Narbonne in southwestern France who is suspected of being the ringleader of the illicit trade, police sources said.
Sanofi said it was cooperating with the investigation into "possible fraud" but played down the possibility of a threat to human health.
The company said it had sold around 200 horses in the last three years, generally to veterinary colleges, individuals or horse centres.
"The horses are all micro-chipped for tracability and they do not present any danger in the event of human consumption," a spokesman said.
"It is specified in their sales certificates that these horses are not to be introduced to the food chain, but that is as a precautionary measure, not because there is any danger."
The company said that the horses had been used to provide blood for the manufacture of serums against tetanus and rabies and stressed they had not been used for drugs testing.
A police source also indicated that there was no evidence of a risk to human health "but they should never have found their way on to diners' plates".
The case follows a Europe-wide health scare earlier this year when horsemeat was found in millions of ready meals labelled as containing only beef.
Benoit Hamon, the French minister responsible for consumer affairs, said the latest episode was potentially more worrying than the labelling scandal, which centred on a French company, Spanghero.
"It's different. In this case there could be a health problem," Hamon told RTL radio.
But Food Minister Guillaume Garot played down that idea. "At this stage there is nothing to indicate any health problem," he told AFP.
Eating horsemeat is regarded as taboo in some European countries, notably Britain, but is still widespread in Belgium, France, Spain and Italy, although consumption is in long-term decline.