China has not decided on a schedule for the commercial planting of new varieties of genetically modified crops, despite the rapid approach of expiration dates for its two strains of GM rice, said a senior agricultural officials on Wednesday.

Domestic debate over the safety of GM food has grown since the Ministry of Agriculture issued biosafety certificates to two strains of pest-resistant GM rice in 2009.

The expiration dates are listed on the biosafety certificates, and planting and harvesting should take place before the specified dates.

According to the ministry, the strains still need registration and production trials before commercial planting can begin — and those trials could take between three and five years.

However, the certificates will expire in August, according to Huazhong Agricultural University, the developer of the two strains.

"Government authorities should ensure the safety of GM food before promotion, and so far, we do not have a time schedule for the commercial planting of these GM crops," said Chen Xiaohua, vice-minister of agriculture.

However, Chen said at a press conference that the country will boost its scientific research efforts in the sector, with the aim of developing new varieties of GM crops by itself.

So far, the country has issued biosafety certificates for various GM strains of cotton, rice, corn and papaya, among which only cotton and papaya are allowed to be commercially planted.

Statistics from the ministry on Wednesday showed that 96.6 percent of its monitored vegetables in the domestic market met quality standards in 2013, while the rate for animal products was 99.7 percent and that for aquatic products was 94.4 percent.