Proposed changes to China's regulations on genetically modified organisms (GMO) could further delay an already lengthy approval process for imports of new GMO crops, plant science industry association CropLife Asia said.

China's Ministry of Agriculture revealed plans to amend its regulations on GMOs last month, which was seen as an attempt to reassure consumers concerned about the contamination of conventional foods with GMOs.

The changes, open for public comment until May 24, include the removal of fixed periods for the submission and review of new GMO crops, which is likely to result in further delays for seed firms, said CropLife Asia, whose members include Monsanto, Bayer CropScience and DuPont .

"We have particular concerns about the amendments to articles 16 and 22 since they are likely to have significant negative impacts on the timeliness, predictability and transparency of the Chinese agricultural biotechnology approvals system," said executive director Siang Hee Tan.

Current law stipulates three deadlines for the submission of GMO crops for approval each year - March 1, July 1 and Nov. 1. At each deadline, an expert biosafety committee meets to review pending applications.

The Ministry of Agriculture issues official approvals at a later date based on the committee's assessment.

The new version of the law includes no such fixed dates for reviewing applications. It also has a clause saying the ministry will consider "scientific, economic and social factors" in its decision-making, broadening it out from scientific considerations.

The ministry did not respond to a request for comment on the changes.

China, the world's largest soybean importer, has been taking longer to approve new biotech crops amid misgivings among the public about GMO food.

It took five years to approve a GMO corn made by Syngenta, known as MIR162, and seven years to pass Bayer's LL55 Liberty Link soybean.

Before the approval of MIR162 in December, more than 1.4 million tonnes of U.S. corn containing the unapproved strain was rejected at Chinese ports, causing large losses for trading firms and triggering lawsuits against Syngenta.

The Ministry of Agriculture also delayed approval of a soybean variety last year, citing negative public opinion, believed to be the first time it had given such a reason for delaying a decision on a GMO product.

International firms voiced concern about the "arbitrary nature" of China's approval system in an American Chamber of Commerce report in February, noting that in practice new products were only being reviewed once a year.

Tan said there were "clear inconsistencies" with World Trade Organization rules on phytosanitary agreements and trade, which should be conducted according to a scientific process and without undue delay.