MORE than half of eggs produced in Britain will be free-range within five years, experts predict.

The increase from the current 33 per cent will follow new EU restrictions on the use of hen cages.

Growing demand from UK retailers is another factor in the expansion of free-range eggs, according to National Farmers' Union poultry board chairman Charles Bourns.

It is expected to account for 55 per cent of British egg production by 2012, This growth will mean another nine million hens being kept free-range.

Mr Bourns said the extra land for the freerange increase was already causing problems with planning permission.

"People have to make up their mind whether they want organic, free-range farming. If they do, they have got to stop this nimbyism, " he said.

Free-range hens must be housed in buildings with plenty of ventilation and natural light, and have access to open-air runs.

Eggs marketed as the most "low-carbon" available in UK supermarkets go on sale nationally today. The "Respectful" free-range eggs are produced on farms supplied with wind and solar-generated electricity.

The eggs come from flocks of up to 4,000 birds kept in Lincolnshire, where they are fed on locally-sourced grain.