Horse meat imported from Poland into the Czech Republic has tested positive for the anti-inflammatory drug Phenylbutazone, which is banned from entering the human food chain.
The Czech Republic veterinary authority reported the finding.
Spokesman Josef Duben said the drug residue was detected in correctly labeled horse meat being sold in a shop in Ostrava, near the Polish border.
They have identified about 300 kilograms of meat in the shipment to date which was delivered to the shop.
Europe has been embroiled in a horse-meat contamination scandal in recent months, which has resulted in tens of millions of ready-to-eat processed beef products being pulled from store shelves in at least a dozen nations.
The scandal has revealed the complexities of the food chain and the potential vulnerability of the system to rogue traders.