The British researchers say the current system used in Europe and the United States is seriously flawed. They want GM foods to go through extra tests, similar to those applied to new drugs, before they reach the supermarket shelves.

But the UK Government dismissed the call saying the researchers were not experts in GM technology and that the UK had one of the toughest regulatory systems in the world.

"Substantial equivalence"

At the moment, GM foods are passed fit if they are deemed to be "substantially equivalent" to the "natural" products on which they are based.

Science policy researcher Erik Millstone, from the University of Sussex, Brighton, public health expert Eric Brunner, from University College London, and Sue Mayer, from the pressure group GeneWatch UK, argue in the journal Nature that this approach is "misguided" and unscientific.

"What substantial equivalence does is assess the safety of GM foods by looking at the chemical similarity to the 'naturally-produced' food, and we're saying that isn't adequate evidence to say that it's safe for human consumption," Dr Mayer told the BBC.

Dr Erik Millstone and Dr Peter Kearns discuss the issues

The team believes the present system should now be abandoned in favour of further biological, toxicological and immunological tests.

The team claims the concept of substantial equivalence is unacceptably vague. The degree to which a GM food must differ from the "natural" product before its "substance" ceases to be acceptably "equivalent" has never been defined and agreed by legislators, they say.

'Unkown risks'

They claim the adoption of "substantial equivalence" has assisted biotechnology companies by speeding up market place access for their products by at least five years. It also slashed millions of dollars off the cost of research and development. All this has happened, they write in Nature, even though the relationship between genetics, chemical composition and toxicological risk remain largely unknown.

"Relying on the concept of substantial equivalence is therefore merely wishful thinking: it is tantamount to pretending to have adequate grounds on which to judge whether or not products are safe."

"If policymakers are to provide consumers with adequate protection, and genuinely to reassure them, then the concept of substantial equivalence will need to be abandoned rather than merely supplemented.

"It should be replaced with a practical approach that would actively investigate the safety and toxicology of GM foods rather than merely taking them for granted, and which could give due consideration to public-health principles as well as to industrial interests."

Replying to the article, a UK Government spokesman said in a statement from the Cabinet Office: "We have one of the toughest regulatory systems in the world. No GM food is approved unless our top scientific advisers are 100% certain that it is as safe as its conventional counterpart.