China is investigating whether more than 20 children were fed genetically modified rice in a project that involved Chinese and US researchers, state media said Tuesday.

The Chinese Center for Disease Control and Prevention had also suspended a researcher, Yin Shi'an, for his involvement in the project after claims that "Golden Rice" was given to children, the official Xinhua news agency said.

Environmental group Greenpeace International last month said that the modified rice, which aims to address Vitamin A deficiency, was fed to 24 children aged between six and eight in 2008.

Greenpeace said the US researchers involved in the project were affiliated with the Human Nutrition Research Center on Aging, which is based at Tufts University in Boston.

The Chinese Center for Disease Control denied it had approved or participated in the research trial, Xinhua reported.

It added a research paper on the trial, which appeared in the "American Journal of Clinical Nutrition", was not submitted to China's health ministry for approval.

In a statement in August, Greenpeace called for an investigation and said the experiment took place in China's central province of Hunan in 2008.

"It is incredibly disturbing to think that an American research body used Chinese children as guinea pigs for genetically engineered food," it said.

Supporters say Golden Rice, which appears yellow or orange in colour, could help reduce child mortality by providing Vitamin A to those lacking it from their diets.