As concern grows about passengers dying from deep vein thrombosis (DVT) after long flights, British Airways said there is no proof that flying itself is a medical risk.

The condition, known as "economy class syndrome'' because it is thought to pose the greatest threat to economy passengers in cramped seats, has hit the headlines in the past year.

The London-based Daily Telegraph reported that at least one passenger dies from blood clots in the leg each month within minutes of landing at Heathrow Airport.

The newspaper reported that doctors believe this is the tip of the iceberg and think more than 2,000 people in Britain die each year from flight-related deep vein thrombosis.

More than a 1,000 people have contacted an Australian law firm to prepare a class action lawsuit against 20 of the world's leading airlines, including British Airways, over DVT.

Earlier this month doctors accused the airlines of covering up the dangers of DVT for more than 30 years.

BA, the only airline flying from the Island to Britain, said it is concerned about DVT, but states the medical community believes immobility rather than environment is the cause.

In a statement, BA said: "We recognise the growing concern over DVT and there is sometimes conflicting information.

"At present, there is no firm evidence that flying is a specific risk in itself.

"There is a shared view among the medical community that it is immobility rather than the environment which is the key factor.'' BA has always provided medical advice to customers and will continue to do so.

The airline had given evidence to a recent House of Lords hearing in London into the health effects of travelling in commercial aircraft. Because long haul flights involved passengers sitting for extended periods, the airline had issued advice about taking simple exercises while seated or taking a short stroll in the cabin.

"The airline is keen to learn more about DVT and we are currently talking to several research establishments about how we can support them in furthering their research into this issue,'' the statement continued.

"In the next few weeks a representative from the airline's health services department will be attending a meeting with medical experts from around the world to discuss research into the issue to date. It is hoped this forum will provide a greater understanding.''