An MP has renewed calls for a public inquiry into the deaths of air travellers from blood clots following the cancellation of a planned study by the World Health Organisation.

John Smith, the Vale of Glamorgan MP and chair of the deep vein thrombosis (DVT) awareness group at Westminster, called it a major setback to investigating links between the condition and air travel deaths.

The condition hit the headlines when 28-year-old Emma Christoffersen from Newport collapsed and died in October 2000 after a 20-hour flight from Australia to Britain.

MP John Smith wants a public inquiry into DVT

The WHO had planned a study of 200,000 frequent fliers to investigate the so-called 'economy class syndrome', or blood clots which form in the legs and travel to the lungs, causing death in some passengers.

But according to Mr Smith, they have had to shelve the study, substituting two other investigations which he said were only of limited value.

The MP became a prominent campaigner on DVT after one of his constituents, a 30-year-old policeman, died on return from an international flight on his honeymoon.

Mr Smith told BBC Radio Wales: "It's a major setback that the World Health Organisation will not now be carrying out the major study.

"That is, taking 200,000 frequent airline travellers to see how many of them actually get DVT.

We know a large number of British people are dying from this condition

John Smith MP

"Quite frankly, it's because they haven't got enough money even though the British government has put two million euros into this research project.

He said the substituted studies were limited in scope and would not provide "serious conclusions" that were needed.

"We have been in touch with the WHO this week and they have confirmed that this, the most important piece of research that will determine exactly how many people get this condition and the most likely cause, will not take place," he said.

Both the WHO and other governments, who had not given their promised share of funding towards the research, were to blame for the survey's withdrawal, he claimed.

DVT victim Emma Christoffersen, 28

"Our government in fact has put money up and the position is that that money is now not going to be spent properly.

"We're not going to find out what the proper state of affairs is," said Mr Smith.

He is now calling for a independent British inquiry into the cause of the condition.

"We know a large number of British people are dying from this condition.

We estimate that it is as many as 1,500 preventable deaths from pulmonary embolisms every year - something has to be done."

A group of 56 people who suffered DVT while flying or the families of victims are fighting a landmark legal case against 28 airlines for failing to warn them of the about the risks of the condition.

If they are successful, airlines could have to pay significant damages to victims or their families.