Around 125,000 restaurants and fast-food outlets will be given six months to prepare for the introduction of the new rules.
Supermarkets will be required from today to ensure that maize and soya products made since last September are properly labelled.
Jeff Rooker, the Agriculture minister, said that by including the catering industry, Britain was leading the rest of Europe, which has limited the European Union regulations to supermarkets and shops.
Environmental campaigners branded government regulations on labelling genetically modified food a "con trick on the public" after Mr Rooker confirmed that it could not stop all GM contamination.
He explained that the new powers did not cover the labelling of GM tomato paste, currently on sale in Britain, or GM derivatives such as soya oil and the emulsifier lecithin. He said that if the tomato paste was used in food outlets such as pizza restaurants he believed the owners would have a "moral obligation" to inform customers.
Mr Rooker added that derivatives were not included as it was virtually impossible to conduct scientific tests to verify their presence in food stuffs.
Paul Tyler, the Liberal Democrat spokesman, warned: "The Government must not use a half-baked labelling policy as a fig leaf for not having a more general policy on GM food. If the Government cannot guarantee products are not free of GM then labelling will not be of any use."
A spokesman for Greenpeace told Mr Rooker at the launch of the regulations: "You are conning the public by saying there is consumer choice because these regulations are going to be irrelevant."
Mr Rooker replied: "I don't accept this is fudging at all ... The Government is determined that consumers should be able to choose whether or not to eat genetically modified foods. This includes foods sold in restaurants, cafes and takeaways and not just that available from supermarkets."
Some restaurateurs believe the laws will be impossible for them to police, because of the difficulty identifying whether bread or other products contain GM foods. Others face confusion over whether they are covered by the new laws.
"How are we going to know whether it's GM or not?" said a vegetable stallholder by Smith Square where the Ministry of Agriculture Fisheries and Food has its headquarters. Fresh vegetables are not covered by the regulations, but the corner sandwich shop serving the ministry civil servants will be covered, if its bread contains GM soya.
Under the new rules, first revealed in The Independent, restaurants and fast-food outlets will not be required to include GM labelling on their menus, but they will have to inform customers who ask whether their food contains GM maize or soya. Consumer standards officers will carry out checks, and firms face prosecution for misinforming the public. Pre-packed foods, such as sandwiches in packets, will be exempt.Reuse content