Beijing's approval process for GMO grains has become "overly political", "unpredictable and non-transparent", an American industry group said yesterday, in the strongest criticism of mainland biotech policy since officials began rejecting thousands of tonnes of genetically modified corn last year. "In recent years, China's biotech approval process has gone from being slow but predictable to even slower, unpredictable and non-transparent," said the American Chamber of Commerce in a policy report. China is the world's top importer of soya beans and among the top importers of corn. All of its soya bean imports are genetically modified. However, it rejected around a fifth of its corn imports last year after they were found to contain Syngenta's MIR612 gene, which has not been approved by Beijing. China's approval of GMO crops for import has slowed from around two years to three years or longer, said David Yeh, vice-chairman of the group's agriculture forum. Delayed approvals are a "major disruption to trade flows", said the report. "AmCham China members are concerned that the approval process has become overly political, requiring high-level attention to advance applications through the [Ministry of Agriculture]," it added. The group's members include leading seed firms Monsanto, Bayer CropScience, Syngenta and DuPont. China has long adopted a cautious attitude to genetically modified crops. Wary of public distrust of the technology, it has not yet allowed any major GMO food crops to be grown in the country, despite investing billions of yuan in research. Yeh said Beijing's strategic focus on ensuring food security may also be influencing its approach to GMO imports.