A retired judge leading an independent inquiry into reports of Gulf War syndrome has promised it 'will succeed' - even without government cooperation.
Some 700,000 troops served in the first Gulf War
Lord Lloyd of Berwick's hearing is to examine the cases of thousands of British troops who reportedly suffered ill health after the first Gulf War.
Veterans have expressed concern the Ministry of Defence (MoD) may not co-operate with the three-week inquiry.
Lord Lloyd said even without the MoD's evidence, the study would get results.
The 75-year-old former Lord Justice of Appeal was asked to head the inquiry by Lord Morris of Manchester, who is honorary parliamentary advisor to the British Legion.
It aims to take evidence from 30 ex-servicemen, medical experts and government representatives.
Lord Lloyd said on Tuesday he had written to the MoD and Ministry of Health but had received only an acknowledgement so far.
He said: "I think it will succeed even if they don't give evidence but I cannot emphasise enough that in our view it is important, indeed essential, that they should accept.
Cocktail of tablets
"Nor do I have any reason to suppose they won't give evidence.
"They have been cooperative in the past and they, like us, are as concerned to find out the facts relating to these illnesses as everybody else."
Thousands of Gulf War veterans say they have suffered from unexplained ailments including kidney pains, memory loss, chronic fatigue and mood swings.
They blame a cocktail of tablets and vaccinations they were given to protect them against nerve agents, anthrax and botulism.
The Legion first called for a public inquiry into the illnesses surrounding the 1991-1992 Gulf War veterans seven years ago - and has made repeated requests since.
But the Ministry of Defence maintains the illnesses are so varied there can be no distinct syndrome or a specific cause.
Lord Lloyd said the government's decision to postpone holding a public inquiry because research was still under way was "not sufficient".
He said: "Certainly after this length of time it ought to be possible to reach some conclusions as to the possible causes of these illnesses."
But his own investigation, funded by an anonymous donor, will not use the term "Gulf War syndrome" because there might not be one underlying cause for all the conditions.
Ian Townsend, the Legion's secretary general, said he hoped the inquiry would provide answers for veterans.
Liberal Democrat leader Charles Kennedy, in a letter to Lord Morris, described it as "long overdue" and said he hoped it would bring closure to the families whose lives it had "devastated".
Charles Plumridge, of the National Gulf Veterans and Families Association, welcomed the hearing but questioned the MoD's willingness to take part.
He said: "We're sceptical of the MoD involvement in this inquiry.
"We simply ask the MoD to come forward, answer pertinent questions and give information which will draw this inquiry to a satisfactory conclusion."