Club Direct is warning travellers of the dangers of deep vein thrombosis (DVT) following allegations that airlines are not alerting passengers to the potentially fatal dangers posed by long-haul flights.

The move comes as a group of at least ten victims and relatives of passengers who have suffered the condition are planning to sue the airlines concerned, accusing companies such as British Airways, Air France, Qantas, Emirates and Air New Zealand of failing to warn them of the dangers.

DVT involves the formation of a blood clot in the leg. Sufferers are not always aware that a clot has formed and, on occasion, people have collapsed shortly after leaving the aircraft. This is because the clot can move from the leg to the lung, a condition known as pulmonary embolism.

From this week onwards, Club Direct will be including an advisory leaflet in all policy packs sent to customers. The information will be sent to all passengers, regardless of the length of their proposed flight. It includes details of the causes and warning signs of DVT on flights and precautions which can be taken to avoid the condition.