An investigation into a widely panned US-China joint project that used dozens of Chinese children as guinea pigs for a new type of genetically modified rice is getting more and more complicated as different allegations spring up.

Case of GM rice fed kids grows convoluted.[File photo]

Twenty-four rural pupils in Hunan Province are said to have been fed genetically modified "Golden Rice" in a nutrition research program led by Tang Guangwen, a professor from Massachusetts-based Tufts University. Parents said their children, aged between six and eight, had their blood drawn five times in the three-week testing period, but the whereabouts of their blood samples remains unknown, China Business reported yesterday.

The school said blood samples were just for routine physical checkups and never showed the results to parents, they said.

The Hengyang City Center for Disease Control and Prevention denied allegations that they ever entrusted the Jiangkou Town healthcare center to take the children's blood samples. "We neither participated in the trial nor had any clues," it said.

Tang said he took blood samples to the United States.

The denial of the province's CDC echoed earlier statements of the Hengyang government and Chinese Center for Disease Control and Prevention.

However, Zhang Lingling, mother of a girl in the second grade at the time, said officials with the province's CDC were present when the school held a meeting with parents to persuade them to agree to the study. Also among them, she said, was Yin Shi'an, a national CDC official listed as the third author on the paper, who is under the investigation for involvement in the project.

Zhang was told that a total of 72 children were picked to have meals that were said to be nutritious. They were fed either genetically modified Golden Rice, spinach or carotene capsules, according to Tufts University.

Many parents signed the agreement without going through the terms or knowing genetically modified food was involved, Zhang added.

Parents of the children also expressed fears over whether there might be risks with genetically modified food.

"I only learned the news a few days ago. I am very worried because it seems that no one can clearly explain what happened," said a parent surnamed Liu, whose 11-year-old was said to have taken part in the program.

Parents are frustrated by slow progress of an official investigation launched in August.