Michael Meacher, the Environment minister, admitted yesterday that the publication on Christmas Eve of a crucial government study on contamination by genetically modified crops was a mistake.
But Mr Meacher denied his department had deliberately tried to "bury" the report detailing evidence that GM crops grown experimentally in Britain had contaminated conventional crops and weeds.
The report found evidence that wild turnip, a weed, was contaminated by genes from GM oilseed rape when they were planted side by side. This could lead to the development of herbicide-resistant hybrids that are difficult to kill.
The report is a setback for the Government, which next year will have to take a crucial decision on whether to press ahead with commercial planting of GM crops.
Mr Meacher, speaking on BBC Radio 4, said he entirely agreed that the "Christmas Eve timing was unfortunate". He said the decision to release the report hours before the only day of the year on which newspapers were not published was a blunder rather than an attempt to conceal its findings. "We weren't trying to bury it," he said.
"It is another case of cock-up rather than conspiracy."
Mr Meacher said he had not been told the report would be issued and admitted the timing looked conspiratorial. "The Kremlinologists are going to have a field day about this." Mr Meacher said the study, which included six years of data, confirmed evidence from overseas that GM crops could breed with native species, creating hybrids.
"The fact is, this information has been known since the early 1990s," he said. "These findings are not new, they simply confirm what was already known. You can't eliminate cross- contamination, you can only minimise it, and try to keep it below a level which is acceptable to the public if they are going to buy the product."