But Sir Robert May said some genetically-modified crops had contributed to increasing antibiotic resistance.

He told the Environmental Audit Committee on Genetically-Modified Organisms and the Environment that "almost anything we eat today would be almost unrecognisable by its earlier, wilder relatives".

Sir Robert said GM technology permitted crop-breeders to be more specific in the genes they introduced to a crop.

"If you want a one-sentence soundbite, I would say I have no more worries about GM technology producing super-weeds any more than I have worries about ordinary crop breeding producing super-weeds, which I think is more likely."

Antibiotic resistance threat

He said both GM crops and the fears surrounding them had existed since the 1970s. Since then, more than 25,000 field studies had been carried out.

"Broadly, one has not yet found something which looks like a serious problem," Sir Robert said.

"I don't believe that what is good for Monsanto is good for the world, but that doesn't mean I'm against the new agricultural revolution."

The greater threat posed by GM technology was the introduction of antibiotic resistance marker genes in some early crops.

"There is a credible worry that this could be one more drop in the large bucket that is antibiotic resistance," Sir Robert said.

Until advances in medicine surpassed the problem of increased human resistance to antibiotics this should be taken seriously. For this reason, Britain had opposed planting of such crops in Spain.

Feeding a 'super-abundant population'

The chief scientific officer argued the need to feed a growing world population justified the quest for new GM crops.

He pointed out that next year 60 million hectares in the world would be sown with GM crops, while the United Kingdom still has no commercial GM plantations.

Britain should strive to be a leading player, which would allow it to bring influence on the multi-national companies involved, but had to accept the technology would progress regardless.

"It's a risk that's being taken on our behalf elsewhere in the world and we ought to keep that in mind," Sir Robert said.

"It is true that today the problem of feeding people well is a problem of distribution not of production, but that would not be true had it not been for the green revolution.

"Over the last 30 years, we've virtually doubled the world production of food and we've done that through high-yielding crops that have downsides.

"If we look 50 years ahead to another doubling of the world population and a slowing down of the green revolution, then I don't see feeding. To my mind, that is the important question."