Three Chinese citizens are taking China's Ministry of Agriculture to court in a bid to make public a toxicology report supporting the approval of Monsanto's popular weedkiller, Roundup, 27 years ago.

The case, a rare example of a lawsuit by private citizens against the Chinese government, comes amid renewed attention on glyphosate, the key ingredient in Roundup, after a controversial report by a World Health Organisation group in March found it to be "probably carcinogenic to humans" - a claim denied by Monsanto.

It also underlines the deep-seated fears held by some Chinese over genetically modified food.

Beijing No.3 Intermediate People's Court had accepted the case but a date for a hearing has not yet been set, an official at the court told Reuters.

Roundup is widely used on crops like soybeans that are genetically modified to resist its impact, allowing farmers to kill weeds without killing their crops. China imports about 65 percent of the world's traded soybeans.

"The government is taking actions to deal with other food safety issues but it is not dealing with the GMO problem," said Yang Xiaolu, 62, one of the plaintiffs bringing the case and a long-time GMO activist.

Monsanto officials have said glyphosate has been proven safe for decades, and the company has demanded a retraction from the WHO over its recent report.

Yang and the other plaintiffs, Li Xiangzhen and Tian Xiangping, are demanding in the lawsuit that the agriculture ministry make public the animal test that the ministry cited as evidence to support its approval of Roundup in 1988.

The test report by U.S.-based Younger Laboratories in 1985 was provided by Monsanto to the ministry, according to the plaintiffs, who argue that the ministry should allow the public to know how it determined that Roundup was safe.

The ministry has previously declined to show the plaintiffs the report, arguing that it would infringe on Monsanto's commercial secrets, said Yang.

The agriculture ministry did not respond to a fax seeking comment.

The lawsuit comes at a time when the government is trying to foster positive public opinion of GMO food crops, currently banned for cultivation, but seen as crucial to future food security.

GMO seeds under development for China include those that are resistant to glyphosate.

Yang is one of a growing number of activists lodging information disclosure requests amid government promises to become more transparent.

The central government has pledged at recent high-level meetings to improve the rule of law and to step up transparency on sensitive issues such as pollution.

But underscoring the difficulty in challenging the government a Beijing court this week ruled against a similar demand by lawyer Huang Leping for the agriculture ministry to disclose more detail on its imports of genetically modified crops and plans for allowing cultivation in China.

In the case sparked by the latest lawsuit, the court notified the plaintiffs that Monsanto would be added as a party to the case, said Yang. Monsanto Asia corporate affairs director Yong Gao said he had received no communication from the court and declined to comment on the case.

The company made 5.3 percent of its $15.9 billion in revenues last year from Asia-Pacific markets. The firm's last relevant patent on glyphosate expired in 2000 and China is now the biggest producer of the herbicide.