Airlines could face a raft of lawsuits from passengers who have suffered deep vein thrombosis (DVT), after a British Airways medical officer admitted that airlines had known about the condition for years.

Professor Sam Shuster of Newcastle University said airlines had not properly explained to passengers the link between long-haul flights and the risk of potentially fatal blood clots forming in the legs.

British Airways accepted the link in the early 1990s and issued advice to passengers about exercising during flights. But the in-flight advice only mentioned “circulatory problems”, because some passengers might not understand the term DVT.

One aviation broker said airlines should pay out on legitimate claims, as they had a duty to carry people in a safe manner and inform them of any risks.

But Tim Brymer, head of aviation at law firm Cameron McKenna, which has conducted a discussion forum on DVT, said it was unlikely that many claims would be successful.

“Claims would put a burden on airlines, as they have to carry people with all sorts of ailments and complaints. Unless the passenger can prove that the DVT was caused by the flight and not a pre-existing condition, there is no claim,” he said.

It is estimated that as many as one in ten long-haul flight passengers may suffer the condition, and 1,000 British passengers a year could be killed by it.

DVT has been brought into the limelight by a number of high-profile incidents, including one in which a woman died during a flight to Australia last year.