China has rejected 545,000 tons of imported U.S. corn found to contain an unapproved genetically modified strain, the country's product safety agency announced Friday.
China's government is promoting genetically modified crops to increase food production. But it faces opposition from critics who question their safety, especially those imported from the United States.
An unapproved strain called MIR162 was found in 12 batches of corn at six inspection stations, according to the Administration of Quality Supervision, Inspection and Quarantine. It said the shipments would be returned to the United States.
In a statement, the agency called on U.S. authorities to strengthen controls on corn exports to ensure unapproved strains are not sent to China.
China allowed its first imports of a genetically modified crop, soybeans, in 1997. Authorities are trying to develop others that produce bigger yields or can resist insects without use of pesticides.
An announcement in June that regulators had approved imports of three new types of modified soybeans prompted an outcry by opponents who said they might be dangerous. The Ministry of Agriculture has launched a publicity campaign to dispel concerns and says the criticisms are unfounded.
U.S. officials were in Beijing this week for trade talks. One participant, Agriculture Secretary Tom Vilsack, said earlier that U.S. officials hope they "help open even more markets for U.S. exports."