China's quarantine authority has rejected 1.12 million metric tons of imported corn from the United States since October, after detecting an unapproved genetically modified strain in shipments, a spokesman said on Tuesday.

As of April 21, quarantine authorities have detected the MIR 162 strain, a GM strain yet to be approved by the country's agricultural authorities, in more than 1.124 million tons of corn shipments from the US and have rejected all of them, said Chen Xitong, spokesman for the General Administration of Quality Supervision, Inspection and Quarantine.

The MIR 162 strain was first detected by the quarantine authority in Shenzhen, Guangdong province, in October.

China's rejections of US corn have cost the US agriculture industry up to $2.9 billion, Reuters reported, citing the National Grain and Feed Association in the United States.

China is the world's third-largest buyer of corn, with a yearly import volume of 5 million tons, according to estimates by the US Agricultural Department.

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