According to Chen, Yin Shi'an, listed in the paper as the third author, is with the China CDC.

Wang Lin, information director of the China CDC, declined to comment.

Chen said his center will continue its investigation and contact the journal about the issue.

A Greenpeace report says 24 Chinese kids have been used for a U.S. GM rice experiment.

Andrea Grossman, a public-relations officer for Tufts University's Human Nutrition Research Center on Aging, however, was quoted by Beijing Youth Daily on Saturday as saying that the monthlong research on golden rice was approved by authorities in both countries after an examination by ethics committees.

Feeding trials with human adults in China have also been carried out to measure the effect of fat in the diet, on bioconversion and bioavailability, according to the Golden Rice Project website, the official golden-rice homepage supported by the Rockefeller Foundation.

On Thursday, Greenpeace, the international environmental campaign group, reported the study, backed by the US Department of Agriculture, which involved feeding golden rice to 6- to 8-year-old children in Hunan.

The study, assigned to the Hunan CDC by the China CDC in 2008, selected 68 primary-school children in a school in Hankou township of Hengyang city.

According to the Hunan CDC, the study was listed as on the Program of National Natural Science Foundation of China.

After the discovery was posted on Sina Weibo, a Chinese micro-blogging website, the news received massive attention online.

After an investigation, the publicity department of Hengyang said on Saturday that there had been no such research project on golden rice. It said on its micro blog there was instead a study on the transformation of carotene in vegetables to vitamin A in children's bodies.

According to Chen Peihou, all results were submitted to the China CDC immediately after the experiment ended, and no paper on that has been published within the country.

Worldwide, debates on long-term safety for GM food continues.

In China, the Ministry of Agriculture in 2009 issued biosafety certificates to two strains of pest-resistant genetically modified rice and corn in what was considered a major development in promoting the research and planting of GM crops.