"More and more food is being trucked, shipped and flown around the world these days, consuming huge amounts of fuel," said Vicki Hird, policy director at the British eco-group Sustain.

"Organic produce is more eco-sustainable but its benefits are undermined by flying the food around the world. You spend more energy transporting it than is saved in its production."

A report released by Sustain this year found that for every calorie contained in that lettuce from the United States, 130 calories of fuel will have been burnt in bringing it to Britain.

A Sustain case study also showed that a basket of 26 imported organic foods could have travelled 240,000 km (150,000 miles) and released as much carbon dioxide as an average home does by cooking meals over eight months.

This applies to non-organic food too. Getting that mozzarella and couscous to British diners eats up 1.6 billion litres of fuel a year, emitting four million tonnes of carbon dioxide.

"People have been led to believe they can have fresh food all year round, not just in-season," Hird said. "They want strawberries at Christmas so they are flown in from California."

ORGANIC FARMING STUMBLES IN BRITAIN

Annual retail sales of organic food in Britain are about one billion pounds, 10 times higher than 1993 and growing by 30 percent a year. But only a quarter is grown at home.

France in contrast, imports just 10 percent of its needs.

"Farmers do not yet have the confidence to convert their production," Hird said. "We need an action plan to give farmers resources and training to move to organic production."

Environmentalists blame also supermarket chains, which they say encouraged the organic boom but failed to encourage local industry by guaranteeing farmers higher prices for the produce.

They say for instance that Britain's largest food retailer Tesco plans to grow organic sales five-fold to one billion pounds by 2006 but still sources 75 percent of produce abroad.

"Most of the big supermarkets don't seem prepared to play their part...If supermarkets are going to keep buying imported organic food, farmers here will be wary of converting," said Sandra Bell, food campaigner for the environmentalist group Friends of the Earth.

As an example, FOE says one chain sources organic butter from Denmark even though organic milk is plentiful in Britain.

Meanwhile, the supermarkets' distribution systems mean that even domestic food may travel the length and breadth of the country before coming back to a store near the farm where it was grown.

SUPERMARKETS STARTING TO SLOWLY ACT

Many chains are now starting to address the issue.

Waitrose now sources 85 percent of its organic food from Britain, while 60 percent of Marks and Spencer's organic food is from British farmers. Sainsbury's pledges to reduce organic food imports to 45 percent by 2004.

Sainsbury's Environment Manager Alison Austin said her company had substantially cut food miles and boosted the proportion of locally grown organic and non-organic food.

"In 2000-2001 we sourced 3.5 percent more products with 0.2 million less kilometres travelled," Austin told Reuters.

"One big driver is that our costs are reduced by doing this so there is a huge business case to cut down on food miles."

The company now buys only British poultry, eggs and dairy products. It says it also is trying to sell produce close to their place of origin - for instance supplying the south of England with vegetables grown in the southern counties of Sussex and Surrey.

"We found that whenever possible, people are keen to buy local produce," Austin said.