BERLIN German authorities said on Friday they had found high levels of a toxin in animal fodder that was produced from maize imported from Serbia, but played down a possible risk to human health.
The discovery of aflatoxin in the shipment coincided with increased concerns over food industry safety amid Europe's horse meat scandal and this week's news that Germany is investigating possible large-scale fraud by organic egg producers.
Authorities in the northern German state of Lower Saxony, a major agricultural hub, said they had halted some 35,000 tonnes of the contaminated shipment at the port of Brake or in warehouses. But a further 10,000 tonnes had already been distributed to more than 3,500 farms in several states.
The feed was meant for pigs, cattle and poultry, it said.
The main threat to human health from any breaching of permissible toxin levels would stem from milk produced by dairy cows but the Lower Saxony farm ministry said stringent quality control levels meant any risk was "improbable".
Aflatoxin, produced by a fungus, is highly carcinogenic.
A spokesman for the federal government in Berlin told a news briefing that Germany had informed other European Union governments and the European Commission of the discovery, in line with EU health and safety rules.
Serbian authorities denied that the original shipment could have contained impermissibly high levels of aflatoxin.
"Our exports adhere to those (international and EU) norms as there is a double control, by both exporters and importers," said Vukosav Sakovic, head of the Serbian association of wheat producers and exporters.
"The probability that they purchased something bad is almost impossible... Out of a total 350,000 tonnes of corn exported in 2012, nothing was sent back and we dealt with some bad batches here in Serbia," he added.
(Reporting by Gareth Jones in Berlin and Aleksandar Vasovic in Belgrade; Editing by Michael Roddy)