China has delayed the introduction of genetically-modified rice and corn as it tries to head off public fears, leading government scientists said on Thursday.

The world's largest rice producer and consumer gave safety approvals to Bt rice and phytase corn in 2009, but has not yet begun commercial production, even though it has already spent billions of yuan on research.

"There are some debates ... We have not given the public enough knowledge about GMO crops," Peng Yufa, a member of the GM crop biosafety committee under the Ministry of Agriculture, told reporters.

"The crops have to be accepted by consumers who are willing to buy and by farmers who are willing to grow," Peng said, adding that the process may take five years.

The public remains "very concerned" about the safety of GM crops, top agricultural official Chen Xiwen said on Thursday, but he added that it was inevitable that China would import GM crops in the future to meet the supply gap.

The large-scale introduction of GMO crops has been seen as a crucial part of China's efforts to feed a fifth of the world's population using less than a tenth of the world's arable land.

But although senior officials have acknowledged the challenges of maintaining food security as the country urbanises, it remains unclear if the new government, to be elected during this session of parliament, will push for the large-scale production of GMO crops.

China is already the world's biggest buyer of GMO soybeans and also the largest grower of GMO cotton.

"We have slowed down, especially since 2009, and that is not normal. It might be fine for Europe to slow down but China can't," Huang Dafang, a researcher with the Biotechnology Research Institute of the Chinese Academy of Agricultural Sciences, told Reuters last week.

"We are hoping to provide our findings (about the efficacy of GM crops) to the new leaders after the NPC."

Beijing-based Origin Agritech, which has exclusive rights to sell phytase corn, earlier has expected commercial production in 2013.

In 2012, developing countries, particularly Brazil, accounted for the first time last year for more than half the global biotech crop area, though the United States remains the top consumer of genetically altered crops.