The British Medical Association, which represents 115,000 doctors, will say the crops should not be grown commercially in Britain until more trials are carried out, arguing that the benefits must be clearly shown before biotechnology companies are allowed to go ahead.
The BMA report, The Impact of Genetic Modification on Agriculture, Food and Health, marks the first official opinion by a British medical body on GM crops. It will call for more testing by independent scientists and for the results to be freely available to the public.
The report, to be published on Tuesday, will say detailed research is needed into possible toxicity of GM food and whether eating it could lead to the development of new allergies and antibiotic resistance in humans.
It will reinforce pressure for a government-backed moratorium on the commercial growing of GM crops in Britain.
The doctors will also cast doubt on the use of data from the United States, where commercial GM crops are already grown, to predict consequences for Britain. The threat of cross-pollination of GM plants could be greater here because the country is smaller and fields are closer together, the report says.
The findings of the BMA's board of science and education will stress that consumers have a right to clear labelling. Its report will call for more comprehensive labelling than the Government has proposed.
The most serious reservations concern lack of knowledge about health implications. The doctors will express doubts about using antibiotic resistance marker genes in GM plants, a common practice. They will call for more rigorous investigations of the dangers of antibiotic resistance and whether that could increase vulnerability to diseases such as meningitis.
Two weeks ago, the Independent on Sunday revealed that the Chief Medical Officer, Sir Liam Donaldson, and the Government's Chief Scientific Adviser, Sir Robert May, had recommended that ministers set up a panel to see if eating GM food could cause birth defects, the creation of new cancers and damage to the immune system.
But their conclusions, which have been read by members of the ministerial committee on genetic engineering, known as MISC6, are being amended by the Government before the report is published.
This has infuriated MPs, who will this week urge Jack Cunningham, Cabinet Office Minister, to publish the report in its original form. They accuse ministers of a cover-up. "The original advice must not be sanitised, it must be published without changes immediately," said Norman Baker, Liberal Democrat environment spokesman.
Ministers fear the report could raise doubts about the Government's handling of the safety issue. A cabinet document, seen by the Independent on Sunday, warned as long ago as February that its conclusions on the effects of GM foods on human health could be serious.
"At its last meeting, MISC6 requested a paper by the CMO/CSA [Chief Medical Officer/Chief Scientific Adviser] on human health implications of GM foods. Will we publish this when it is ready (c April) and use it as a means to explain that GM foods on the market are safe?," the memo asks.
The paper, marked "Restricted - Policy", warns: "What if it shows up any doubts? What can we do? We will be pressured to ban them immediately. What if it says that we need evidence of long term effects? This will look like we are not sure about their safety - we do not monitor consumption of other foods."
GM TREES PLAN, PAGE 10Reuse content