Relatives and victims of those who died from deep vein thrombosis will appeal a High Court ruling that blocked their bid for compensation.

The ruling is a stumbling block for 55 people - including four from Wales - who want to take a case out against 27 airlines for damages.

Des Collins, a lead solicitor for the applicants, criticised the judge's decision but said: "The appeal will be lodged by the end of February."

Mr Justice Nelson ruled on Friday that DVT could not be classed as an "accident" under the terms of the Warsaw Convention.

Emma Christoffersen: DVT victim

The death of Emma Christoffersen, 28, from Newport, two years ago, within hours of getting off a 20-hour flight from Sydney, gave national prominence to the issue of DVT.

But outside the High Court, her mother Ruth Christoffersen reacted angrily to the decision.

"The law is an ass.

"This is not the end of a long struggle to get justice of Emma and other victims.

"Where does justice come into it? Where does their moral responsibility come into it?" she said.

DVT claimants from Wales:

Alison Pendry, of Nant-y-moel, Bridgend, against KLM Royal Dutch Airlines and Northwest Airlines Inc. Timothy Stuart, of Llanmartin, Newport, against British Airways and Quantas Airways Valerie Daley, of Flint, against British Airways and Quantas Airways Peter Williams, of Treorchy, Rhondda, against American Airlines

Announcing his decision at the hearing in London, Mr Justice Nelson said: "I am satisfied that it is appropriate for the line to be drawn. The line should be drawn now."

The claimants will have the right to appeal against the decision.

They have argued the airlines did not properly warn them or their late relatives of the dangers of flying for long hours in cramped conditions.

British Airways has welcomed the ruling by Mr Justice Nelson, saying the legal action by the families is "unfounded".

Ruth Christoffersen attacked the ruling

"We've got every sympathy with the victims of DVT, but since the World Health Organisation and UK courts agree there is no evidence of a specific link between flying and DVT, we will continue to resist such claims," a BA spokesman said.

The death of Emma Christoffersen led to her parents, Ruth and John Christoffersen, helping to set up the Victims of Air Related Deep Vein Thrombosis Association (Varda) to raise awareness of the alleged risks to passengers.

In Australia, a court in Sydney ruled that 59-year-old Brian Povey could take both Qantas and BA to court.

Mr Povey was hospitalised and forced to give up work after suffering an attack of DVT, which he blamed on a three day return business trip from Sydney to London.

Deep vein thrombosis - the facts:

DVT is a condition where a small blood clot forms in the deep veins, particularly in the legs Complications in vital organs can lead to death

More than 40 long-haul airline passengers are known to have died from DVT, which is also known as economy-class syndrome.

But scientists remain divided as to whether there is a definite link.

The airlines involved in the UK action have said that, if the case were to proceed further, they would "vigorously dispute" any allegation that they were to blame.

A spokesman for BA said it would resist any claims against it, in the context of advice given by the government and the WHO that no specific link between flying and DVT had been established.

The airlines said they were protected under the Warsaw Convention from paying compensation for medical problems classed as a "passenger reaction to the normal operation of an aircraft".