An official report on the safety of genetically modified crops has concluded that there are no known risks to human health.

But the government review of the science involved in the issue warns that the absence of evidence of harm is not the same as proof that there are no risks at all over the safety of GM food.

The review was led by Professor Sir David King, the government's chief scientific adviser, working with Professor Howard Dalton, the chief scientific adviser to the environment secretary and with advice from the Food Standards Agency.

"On balance, we conclude that he risks to human health are very low from GM crops currently on the market," the report concluded.

Rather than backing a blanket ban, the panel of 24 senior experts found that judgements on GM planting should be made on a case by case basis.

There was a more cautious assessment of the possible environmental impact of GM crops, however.

The study found that in other countries where GM crops are grown there are "no reports of them causing any significant environmental damage".

But it offered some support to those who fear that weedkiller-resistant modified crops could kill off weeds that other forms of wildlife depend on.

"Above all, this poses perhaps the most serious potential harm arising from these particular crops," the report warned.

King emphasised that GM was not a single "homogenous technology" and that "its applications needed to be considered on a case-by-case basis".

The panel also stressed the importance of GM regulation keeping pace with new developments.

"GM is a subject of intense debate and attracts a wide range of views from supporters who point to the potential benefits to opponents with significant concerns," King said.

"The GM Science Review published today has been unique in the way it has considered in detail the interests and concerns of the public and experts alike.

"I hope that its honest and unbiased findings will enable debate and decision to be informed by sound scientific evidence.

"We cannot know everything but if we are paralysed by uncertainty, innovation and progress will be stifled."

He added that ministers should continue with this approach to the technology in years to come.

"The very best science must be brought to bear on the important decisions that will need to be taken in the future," he said.

"GM technology must not be considered in a vacuum but alongside conventional agricultural and food applications."

But the former environment minister Michael Meacher dismissed the report.

Speaking to the BBC on Monday, he warned against any conclusion that GM crops are low risk.

"There is a yawning hole in this report, namely that they haven't produced the evidence to find out whether that is true or not," he said.

The latest report follows the publication of a separate study that concluded that at present there was little economic benefit to be gained from extending the planting of GM crops across Britain.

But that study warned that the UK could lose out on potential economic benefits if it ruled out all future exploitation of the new food technology.