Agricultural experts and the public are calling on authorities to accelerate progress on information disclosure about genetically modified food as the expiration date of biosafety certificates for two strains of GM rice approaches.

Questions from the public over the safety of GM food have grown in China since the Ministry of Agriculture issued biosafety certificates for two strains of pest-resistant GM rice in 2009.

The strains still need registration and production trials, which will take three to five years, before commercial planting can begin, according to the ministry.

The certificates will expire on Aug 17, 2014, according to Huazhong Agricultural University, the developer of the two strains.

Luo Yunbo, head of College of Food Science and Nutritional Engineering at China Agricultural University, said on Monday that research conducted by his team five years ago showed that pigs suffered no ill effects when fed with GM rice.

"Compared with feeding with non-GM rice, there was no difference in the health condition of the pigs after they were fed with GM rice for 90 days," Luo said.

The research result was meaningful for proving the safety of GM rice as many similarities exist between pigs and human beings.

Similar research was also conducted on rats to prove the safety of GM rice before the Ministry of Agriculture issued biosafety certificates for the two strains of GM rice.

An agricultural expert on GM rice research who declined to give his name said on Monday that test feedings of rhesus monkeys would also be conducted in the near future.

"Since rhesus monkeys have many similarities with humans, the test will help the public further increase their confidence on the safety of GM rice," he said.

In July, more than 60 academicians from the Chinese Academy of Sciences and the Chinese Academy of Engineering submitted a petition to the central government calling for an increase in the production of GM crops.

The petition asked the ministry to push for the planting of GM rice, describing the current GM crop situation in China as extremely grave.

"Whether the two strains of GM rice can be commercialized or not in China will be greatly determined by acceptance by the public," said Huang Dafang, a former member of the biosafety committee in charge of agricultural GM organisms.

Huang is also a researcher from the Biotechnology Research Institute at the Chinese Academy of Agricultural Sciences.

"The growing debate over the safety of GM food in recent years was partly caused by government authorities who failed to disclose related information to the public in a timely manner. Many ordinary people were confused by rumors," he said.

On Sept 12, lawyers from across the country issued an open letter to the China Food and Drug Administration and the Ministry of Agriculture asking them to make related information on GM food in China known to the public.

"The Ministry of Agriculture gave us three websites. One does not open, and we cannot be satisfied with the simple content of the other two. The China Food and Drug Administration said that was not within its jurisdiction," said Shi Baozhong, a lawyer from Anhui province who signed the letter.

The lawyers now expect to re-apply for administrative review, he said.

China has issued biosafety certificates for some GM strains of cotton, rice, corn and papaya, of which only cotton and papaya may be commercially planted.