One of the UK's leading travel operators is set to increase the legroom on their economy long-haul flights by three inches next year, it was announced yesterday.

Thomas Cook decided to up its "seat pitch" - the distance between the back of one seat and the back of the seat in front - from 30 to 33 inches following a recommendation made by the House of Lords last week.

The world's busiest carrier, American Airlines, edges ahead of its rivals with up to 34 inches on its Boeing 777s and 32 inches for the rest of its international flights.

British Airways currently offers 31 inches on a standard transatlantic flight in economy-class, and Virgin Atlantic 32 inches. Australian airline Qantas provides a 31-32 inch seat pitch on a typical 747 flight from London to Sydney.

However, short-haul flights continue to lag behind in the space stakes.

Passengers on Thomas Cook Airlines can expect 28 inches of legroom on a typical short-haul flight, the same as those travelling with First Choice Airways, Thomsonfly and MyTravel.

In the low-cost market, Ryanair and Bmibaby meet the Lords' 30-inch target while Easyjet falls just short at 29 inches.

The reluctance of operators to increase seat pitch on short-haul flights is tied to the narrower profit margins available within the area of the airline business.

A spokesman for Thomas Cook said: "Increases at one end mean drop-offs at the other. More space equals fewer passengers, so the gains and losses have to be evened out."

The airline industry has to balance a trade-off between health and safety on the one hand, and the environmental cost of flying on the other.

Enlarging the seat pitch means fewer passengers, and fewer passengers leads to an increased carbon footprint.

The House of Lords condemned the UK Government's "wrong" policy of charging premium economy passengers the same duty as those in first-class seats.

The duty was widely understood to underline government moves to encourage airlines to fly with more passengers in less space, for green reasons.

The planned increase by Thomas Cook will put the company ahead of its leading UK competitors in the long-distance sector.

The changes will come into effect from May.

MyTravel Airways, which is due to merge with Thomas Cook in March, will also expand leg space in line with the tour operator's decision.

Thomas Cook's expan- ded travel empire will therefore include both Airtours and the MyTravel organisation.

The company anticipates taking some six million people abroad in 2008, to popular destinations such as Majorca, Ibiza, Turkey, Egypt or the Canary Islands.

Long-haul destinations favoured by their customers include Thailand, Barbados and Dubai, while Cuba, Santorini and Jordan are gaining in popularity.

The House of Lords Science and Technology Committee advised Civil Aviation Authority that airlines should widen the space to a minimum of 30 inches to accommodate the increasing size of the average passenger.

They also sought to allay concerns over so-called "economy-class syndrome", whereby passengers on long-haul coach-class flights are thought to increase their risk of DVT (deep vein thrombosis).