LONDON (Reuters) - Research commissioned by Britain's Food Standards Agency has shown that DNA material from genetically modified (GM) crops can find its way into human gut bacteria. Researchers at the University of Newcastle in the north of England said in a report on Wednesday they gave seven volunteers, who had had their lower bowel removed, a single meal of a burger and milkshake containing gene-spliced soya. Samples of intestinal bacteria were taken and for three of the seven, a herbicide-resistance gene from the GM soya was detected at a very low level. Genetically modified material in most GM foods poses no risk to human health, but many GM crops have antibiotic-resistant marker genes inserted in them, raising concerns that the ability to fight infection could be compromised if such material passes to humans. The researchers also cultured bacteria from samples taken before the GM meal was eaten, which also had low levels of the herbicide resistant gene. They noted that it was "surprising" that so much of the GM soya DNA was present after the food passed through in the small intestine, given the digestive processes that occur in the stomach. The researchers also fed the same meal to 12 other human volunteers whose stomachs were intact, but no GM material or bacteria containing herbicide-resistance genes were detected in their feces. An FSA spokeswoman dismissed fears that human resistance to illness could be harmed. "Because we're talking about such low levels of DNA, there's no evidence that this would affect antibiotic resistance, which is why the researchers concluded that the likelihood of DNA being taken up by bacteria in the human gut is extremely low," she said. Environmental pressure group Friends of the Earth ( news - web sites) said the report's findings raised serious questions about the safety of GM crops. "This report should set alarm bells ringing. Industry scientists and Government advisors have always played down the risk of this ever happening, but when scientists looked for it they found it," a spokesman for the group said. "GM food should be withdrawn from the market and further research must be commissioned as a matter of urgency," it added.