Friends of the Earth surveyed 11 leading chains and found all said they did not use GM soya or maize.

The government has ordered all food containing GM ingredients to be labelled from Sunday following implementation of a European Union directive last September.

Caterers, shops, food-makers and restaurants must all comply or face fines.

However, FoE highlighted a loophole in the legislation which meant food outlets could supply meals which contained GM derivatives such as GM lecithin and GM soya oil without having to tell customers.

Supermarkets are removing GM products

Two of the companies surveyed - Pret a Manger and Domino's Pizza - said they had removed GM derivatives while a further six said they were removing them.

Pete Riley, senior food campaigner at FoE, said: "This survey shows that restaurants recognise that customers do not want to eat food containing GM ingredients or derivatives and that most are now removing them as fast as they can.

"However, restaurants might well ask why they have to go to all the trouble and expense to ensure that their meals don't contain ingredients that neither they nor their customers want.

"Surely the bill should be picked up by the big biotech companies who stand to make vast sums of money from this new technology."

Several major supermarket chains, including Sainsury's and Marks and Spencer, are removing all GM ingredients from own-brand ranges.

Their decisions follow that of frozen food retailer Iceland, which announced that none of its own-label produce would contain GM ingredients in April 1998.

'Unaware of deadline'

But Mr Riley said that rather than introducing labelling schemes which were unlikely to be enforced, the government should listen to consumers and back calls for a five-year freeze on GM food and crops.

McDonald's, Perfect Pizza, KFC, Pizza Hut and City Centre Restaurants (which includes Cafe Uno and Deep Pan Pizza) said they were removing GM derivatives.

Wimpy said it would be free of the derivatives by the end of the year while Burger King and Granada said they were monitoring and reviewing the situation.

More than half of the UK's food outlets said they were unaware of the labelling deadline, in a BBC survey last week.

Of 262 food outlets across the country, only 53% said they were aware of the deadline.

The report also found that only 45% said they would be ready to comply with the new regulations in time.

Only 17% said they had received enough information about the new rules and 57% had had none at all.