A group of UK airline passengers representing 56 claims relating to passenger DVT-related deaths and injuries are starting a landmark legal case against 28 airlines for failing to warn them about the risk of deep vein thrombosis.

Their lawyers will argue a combination of cramped flying conditions and long hours in the air can give rise to the condition DVT, also known as economy class syndrome.

The airlines have denied liability, arguing that they are protected under the 70-year-old Warsaw Convention from paying compensation for medical problems classed as a passenger reaction to the normal operation of an aircraft.

The group legal action is aimed at persuading the high court in London that DVT should be classed as an 'accident' under the convention. If successful, this could lead to airlines having to pay out significant damages to victims or their families.

Tips to lower the risk of developing DVT include walking around the aircraft during a flight and wearing tight stockings.