"Zombie" GM crops - so called because farmers will have to pay biotech companies to bring seeds back from the dead - are being developed with British taxpayers' money.

The highly controversial development - part of a £3.4m EU research project - is bound to increase concerns about the modified crops and the devastating effect they could have on Third World farmers.

Environmentalists charge that it appears to be an attempt to get round a worldwide ban on a GM technology so abhorred that even Monsanto has said it will not use it.

The ban is on the so-called "terminator technology", which was designed to modify crops so that they produce only sterile seeds. This would force the 1.4 billion poor farmers who traditionally save seeds from one year's harvest to sow for the following one instead to buy new ones from biotech firms, swelling their profits but increasing poverty and hunger.

Since the ban was agreed under a UN treaty seven years ago, companies and pro-GM countries - including the United States and Britain - have pressed to have it overturned, so far without success. But the new technology promises to offer companies an even more profitable way of achieving dominance.

Zombie crops would also be engineered to produce sterile seed that could be brought back to life with the right treatment - almost certainly with a chemical sold by the company that markets the seed. Farmers would therefore have to pay out, not for new seeds, but to make the ones they saved viable.