Three environmentalists in Beijing have filed a case in Beijing No 3 Intermediate People's Court requesting that the Ministry of Agriculture make public toxicological test reports on the popular weed killer Roundup, a product of US agrochemical giant Monsanto that is in use around the world.

The court action comes a few weeks after an agency of the World Health Organization declared that an ingredient used in Roundup likely causes cancer.

The court accepted the case and included Monsanto as an interested party, Yang Xiaolu, one of the environmentalists, said in an interview on Monday. The court has yet to schedule the case, he said.

The court action was taken after the herbicide glyphosate, the active ingredient in Roundup, was classified as "probably carcinogenic to humans" by The International Agency for Research on Cancer - the cancer specialist of the World Health Organization - based on epidemiological, animal and in vitro studies.

Yang said the fact that glyphosate products are among the most widely used weed killers in China means the ministry and the US company should respond to public concerns over the safety of the product in a timely manner.

"We want to know how Monsanto proved the product was safe for humans - what records were used and how the experiments were conducted," he said.

The environmentalists first made the request on behalf of the public interest to the ministry in February last year. But the ministry said it must first get approval from Monsanto before making the report public. The company declined the request, citing trade secrets.

Toxicological experiments on Roundup were conducted by Younger Laboratories in the United States in 1985, the ministry said.

"I don't think there are commercial secrets that are more important than the health of the general public," said Yang, a businessman interested in food safety and environmental problems. Yang is also an outspoken activist who opposes the promotion of genetically modified foods in China.

Yang said he and the two others decided to take legal action against the ministry because they could not get an answer through normal administrative channels.

A spokeswoman for the China office of Monsanto declined to comment on the court filing on Monday. Robb Fraley, Monsanto's chief technology officer, said in a statement on its website that the company is "outraged" by the assessment made by the WHO agency.

Zhong Nan in Beijing contributed to this story.

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