And organic farmers could face ruin if GM crops are allowed to be grown on a commercial scale in Britain, says the report, now being studied in Whitehall. It warns that organic crops are certain to be contaminated by GM plants because their pollen can spread far beyond the boundaries of fields.
The conclusions of the report, written by biotechnology and agriculture experts at the John Innes Centre in Norwich, have severe implications for Britain's burgeoning organic food sector.
Organic food is defined as being "pesticide and additive free" in Britain and any kind of genetic engineering is banned by the Soil Association, which regulates organic farming.
The report says organic farmers should set standards for acceptable levels of pollution by GM plants and that a system for checking for contamination should be put in place.
"Neither source of contamination, either pollen or seed, can be entirely eliminated, so acceptable levels have to be decided on," says the report.
But organic farmers say that the report supports their view that GM crops pose a serious threat to their livelihoods. They argue that consumer confidence in organic food would inevitably be undermined if even limited contamination was tolerated.
The report, Organic Farming and Gene Transfer from Genetically Modified Crops, examined data from trials of GM crops to see whether the proposed "buffer zones" between fields of GM and organic crops would protect them from contamination.
It asserts that the proposed barriers around ordinary crops could result in up to one per cent of organic plants becoming GM hybrids.
The Soil Association has said that a six-mile barrier is the minimum guarantee that organic crops are not tainted.
"We are determined to maintain the purity of organic crops in the UK and this is why we have set ourselves against GM," said Richard Young of the Soil Association. "The boundaries between GM crops are totally inadequate to protect organic farmers from GM crops. We are about sustainable agriculture working in harmony with nature - not altering it for a quick- fix solution."
GM pollen can travel large distances on the wind, and is also carried by bees. GM seeds can also fall off trucks and farm machinery during transport or be left in the ground, leading to the growth of stray plants.
Ministers have promised to protect Britain's growing organic farming sector from the threat from GM crops. But environmentalists say that organic farmers are being betrayed.
"The Government seems to be about to renege on its promise to protect the organic farmer from genetic pollution," said Pete Riley of Friends of the Earth. "Non-organic farmers hoping to get into the expanding GM free market are also vulnerable to this type of contamination... with organic produce no level of GM contamination is acceptable."