London, Jan. 29 (Reuters): Airlines are dragging their feet in cooperating with a study on whether the so-called economy class syndrome, which causes potentially deadly blood clots, is linked to flying, a leading researcher said today.

One of the scientists in charge of the investigation conducted by the World Health Organisation said the carriers’ slowness had hindered his team’s research. “The airlines’ defensive reaction is counterproductive,” Frits Rosendaal said. An international airline lobby group denied the accusation.

The investigation seeks to prove whether or not the potentially deadly syndrome, known as deep vein thrombosis (DVT), is related to flying and is crucial to airlines and victims battling each other in courts around the world.

“The airlines are not really used to this kind of research. That combined with a defensive position — being scared of publicity, lawsuits or loosing travellers — have helped cause delays...,” he said.

As a result, Rosendaal said, the issuing of questionnaires crucial to a pilot study had been delayed by about five months.

Rosendaal did not say which carriers had been slowing down the study, which needs airlines’ cooperation to analyse hundreds of thousands of fliers over the next few years.

The International Air Transport Association (IATA), which represents the majority of the world’s international carriers, defended the industry and said carriers were doing everything in their power to help with the study.

“The fact is that we are cooperating to the best of our ability and don’t feel that it is fair to accuse the airlines of dragging their feet,” said an association spokeswoman.

“The airlines are ready to go on their part of the study,” she said, adding that two airlines were participating in the pilot study, but declined to say which carriers were involved.

Sources close to the airlines said the two airlines participating in the study are British Airways and Brazil’s flagship airline Varig. BA said it would let IATA speak for it on the subject and Varig could not initially be reached.

A link between DVT — which can cause blood clots in the legs that break away and invade the lungs and heart — and flying would give claimants around the world powerful ammunition to pursue airlines and demand millions of pounds in damages.

Cases in England, Canada, the US and Australia pit DVT sufferers and their families against the world’s leading airlines, including Europe’s largest, British Airways Plc and the world’s biggest, American Airlines.

Ruth Christophersen, whose 28-year-old daughter Emma died after a flight from Australia to Britain, said the airlines’ actions appear to show that airlines are not interested in finding out if there is a link between flying and the ailment.

“I wonder, do the airlines not want an answer? I would have thought that the airlines would have sought to get the study done and not put obstacles in the way,” she said.