DuPont Pioneer, agricultural seed and chemical unit of the US chemical group and one of the world's largest seed companies, is refusing to give up on efforts to cultivate genetically modified crops in Chinese fields, despite regulatory hurdles.

The company recently harvested its first test crops of GMO corn in China in six years after lengthy efforts to win government approval for the new field trials. However, it is pressing ahead while Monsanto is retreating, as it did earlier in the face of European consumer opposition.

China is already a large producer of genetically engineered cotton, but has not approved commercial cultivation for any type of biotech corn. Approval to sell GMO corn seed to Chinese farmers would mark a big victory for a US seed maker because China is the world's fastest-growing corn market.

Industry leaders have told the news agency Reuters they are focusing on winning Chinese clearance for imports of new genetically engineered crops rather than for cultivation approval.

Chinese consumers have become increasingly concerned over GMOs in the past two years, and Beijing has all but stopped issuing approvals for imports of new GMO crops. Another hurdle for Western companies is said to be China's desire to promote its own domestic biotech innovations.

Pioneer is in the first stage of the application process for commercial cultivation of GMO corn, which could take at least six years, Firoz Amijee, who leads the company's efforts to win regulatory approval for new biotech crop products, told Reuters.

Researchers this year have worked with Chinese government scientists to plant, harvest and analyze Pioneer corn genetically altered to control insects and tolerate herbicides.

Pioneer, which has established three joint ventures in China since 2002, was last allowed to conduct similar field trials on GMO corn there in 2008.

Matthew O'Mara, director of international affairs for the Biotechnology Industry Organization, whose members include major seed companies, said cultivation approval for GMO corn was unlikely anytime soon.

Syngenta is facing lawsuits from grain handlers after China rejected imports of US crops containing the Swiss company's GMO corn trait approved in the US but not China.