Belgium health authorities on Friday reported the seizure of 16.8 tonnes of horsemeat, part of it linked to a fresh food scandal in France involving meat not supposed to wind up on people's plates.
France informed Belgium last week of the delivery to a Belgian firm of 17.5 tonnes of falsely-labelled meat from horses that were used by scientists to help produce anti-rabies and other serums.
Police made a score of arrests earlier this month in southern France following a tip-off that 200 horses, including 60 owned by pharmaceutical giant Sanofi, had ended up in abattoirs after their veterinary certificates had been falsified.
Belgian food safety agency AFSCA said in a statement that the meat had been integrated into "a larger consignment of 82 tonnes of horsemeat".
Of the 82 tonnes, which included both regular horsemeat and horsemeat carrying false papers, 63.6 tonnes were "distributed across all of Europe", in particular in France and the Netherlands, AFSCA said.
A total 1.6 tonnes were sold as fresh meat in Belgium in February and March. The remainder was frozen and was seized this week.
French prosecutors have said that though the meat was falsely labelled and should not have been sold, there was no evidence it was harmful to human health.
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.
Sanofi, which has been cleared of any wrong-doing, has said the horses were used to provide blood for the manufacture of serums against tetanus and rabies and stressed they had not been used for drugs testing.
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 decline.