Deng said the World Health Organization and the Council for International Organizations of Medical Sciences have formulated an international standard of ethics related to human biological medical research, adding that the Ministry of Health issued a regulation on human biological medical research in 2007 to strengthen research management.

GM food remains controversial nearly two decades after being introduced to the commercial market, as there is still no consensus on whether or not it is harmful to the human body.

Greenpeace, which informed the parents about the testing, said on its website that it is not known whether genetically engineered crops are safe for human or animal consumption. Independent scientific studies on the matter are severely lacking, it said.

"Until now, no government departments or institutes have publicly spoken about the health risks or lack thereof regarding GM rice. As parents, how can we rest assured?" said a parent surnamed He.

A government report issued by the National Development and Reform Commission last year said China needs to enhance the management of GM food safety, adding that the country's research into the food's toxicology remains in its initial stages.

"Although there is no sufficient evidence to show that it is dangerous, GM food is surrounded by uncertainties regarding its safety. More tests need to be done," the report said.

The report also urged the strict labeling of GM products and increased publicity regarding the products.

It is not yet known if the parents were told that the nutrition research program involved GM food, nor if the testing posed any health risks.

"I wish the claims about GM food health risks were only hearsay. I would be ashamed if anything bad happened to the children, " said He Chongqiu, former principal of the Jiangkou school.