Keeping hens in cages, also known as battery hens, is scheduled to come under an EU-wide ban in 2012. Industry had been calling for a delay but this week the European Commission confirmed the ban will go ahead.

The UK's environment secretary Hilary Benn has also said there is no reason to delay the start of the ban.

But the National Farmers Union says the ban's impact on chicken welfare will be "worse than useless" if the same standards are not applied to imports.

NFU Poultry Board chairman Charles Bourns said egg producers were prepared to accept the battery cage ban as long as it did not lead to the export of the egg industry to countries with lower standards of chicken welfare.

"The fact that the EU has said it is not going to extend the deadline for outlawing the present generation of battery cages does at least remove any uncertainty," said Bourns.

"But it will be pointless and counter-productive if we do not extend the same level of welfare to all of the chickens involved in supplying eggs to the European market, not just those chickens that happen to be housed in the EU."

Last week a series of TV programmes hosted by popular chefs Jamie Oliver and Hugh Fearnsley-Whittingstall showed farmed chickens in the UK living in cramped and dark conditions. The NFU argues that chickens reared for meat in Britain are kept indoors or are free range but never in battery cages. and that the country leads in animal welfare.

The British Egg Industry Council also says that more than 85 per cent of UK egg producers subscribe to its British Lion Code of Practice which sets animal welfare requirements.

But UK retailers earlier this week reiterated their efforts to remove battery-farmed eggs from their shelves and own-brand products. Supermarkets like Morrisons and Sainsbury say they are actively clearing shelves of battery-farmed eggs over welfare concerns and changing legislation.

The announcements highlight the pressure on both farmers and food processors over the growing importance of more ethical food sourcing and livestock treatment to both regulators and consumers.

The NFU also attacked the government for failing to set an example in its own food procurement policies.

"We also want to see the government giving a lead on this issue, instead of applying the same old double standards," said Bourns.

"Government departments are still sourcing over 40 per cent of their food from imports, including products like chicken, eggs, pork and bacon from countries which are still using systems that would either be illegal in this country or which would be unacceptable under our farm assurance protocols."