The move could affect millions of dollars' worth of corn gluten exports.
The dispute centers on a batch of Bt10 genetically modified corn that Swiss agrochemicals company Syngenta AG inadvertently sold in the United States and exported to Europe without approval.
"This is a targeted measure which is necessary to uphold E.U law, maintain consumer confidence and ensure that the unauthorized GMO (genetically modified organism) Bt10 cannot enter the E.U. Imports of maize products which are certified as free of Bt10 will be able to continue," said E.U Health Commissioner Markos Kyprianou.
The ban will effectively shut out all imports of U.S. corn gluten, since there is currently no effective way of testing for Bt10, which has not been approved by American or European regulators. E.U. spokesman Philip Tod said Syngenta was working to develop and validate such a test, but they could not say when it would be ready for use.
U.S. shipments of corn gluten feed to the EU totaled $450 million last year.
"We view the E.U.'s decision to impose a certification requirement on U.S. corn gluten due to the possible, low-level presence of Bt10 corn to be an overreaction," said Edward Kemp, spokesman for the U.S. mission to the EU.
"U.S. regulatory authorities have determined there are no hazards to health, safety or the environment related to Bt10," he added. "The small amounts of Bt10 corn that may have entered the EU have had no proven negative impact."
The ban is to come into force early next week, pending formal approval by the E.U.'s head office.
Chief operating officer of Syngenta Seeds Mike Mack said it would quickly have a workable test for the E.U.
"We will make operational within a matter of days a valid test method to detect for Bt10," Mack said. Such a test would still need further approval from E.U. authorities.
Environmental campaigners welcomed the move. "Europe now has a de facto ban on the import of many U.S. animal feeds," said Friends of the Earth spokesman Adrian Bebb.
However, Greenpeace warned that stricter controls are needed to prevent more cases of unauthorized biotech imports.
"Europe is currently helpless to defend itself from contamination by GMOs that are suspected to harm human health and the environment," said Christoph Then, genetic engineering expert for Greenpeace.
"As long as E.U. authorities have no means to test imports for all the GMOs being released in the U.S. and elsewhere, it must say 'no entry' to the E.U. for any food, feed or seeds that are at risk of contamination."
The E.U. said it is in continuous talks with U.S. authorities on the issue, but its decision to ban suspect corn gluten imports further strains trans-Atlantic trade relations.
By Raf Casert