MADRID/WASHINGTON, Aug 6 – European Union buyers have voluntarily moved to stop imports of U.S. soy after shipments were found containing traces of genetically modified corn, a spokesman for the EU in Washington said on Thursday.

European trade sources said U.S. soybean meal shipments to Spain and Germany were found with traces of GMO corn, which is prohibited in the European Union.

“The industry has itself decided to stop all imports of U.S. soy, as of now,” Mattias Sundholm told Reuters.

“The shipments have been rejected at the EU borders, and have been consigned and recalled when already on the market within the EU, unless they have already been consumed,” Sundholm said.

Sundholm could not confirm the quantity or location of the shipments, but said they were found to contain the corn varieties MON-88017 and MIR-604.

Officials from the U.S. Agriculture Department and trade associations have not replied to requests for information.

The incident has raised concerns about bottlenecks in supply of a key feed ingredient for European livestock, which is already pricey.

“The main problem is that EU regulations don’t allow marginal amounts, traces of GMOs not authorised by the EU,” a spokesman for the Spanish Assocation of Cereal and Products Importers said.

“That puts us all in an uncertain, risky trade situation, and that is most serious for the entire European Community — trade, livestock production and the economy.”

Sources said 50,000 tonnes of contaminated U.S. soybean meal had been unloaded and detained at Tarragona, Spain’s largest port. Port officials were not available to comment.

“It still needs to be dispatched and we await a meeting by the European Commission, probably in September, because nothing will happen in August,” a port source said.

“The meeting will have to be urgent, because they have had similar problems in Germany.”

The EU was the fourth-largest market last year for U.S. soymeal exports, totaling 475,900 tonnes. Shipments so far this marketing year, which began last October, are 374,300 tonnes.