Robert Haley told Lord Lloyd's independent inquiry into war-related injuries that the US government had radically changed its attitude towards his work after other scientists replicated studies indicating brain damage in veterans.

There was a Gulf war syndrome, or at least a group of illnesses attributable to service in the gulf in 1991, he said. His group was now seeing whether experimental results on small groups of veterans could be extended by comparing brain images of veterans with those of others who were not deployed. Britain should join in.

"We don't know how that would play in the United Kingdom", he said. "It would be worth doing to get some brain imagery in this country."

Dr Haley, professor of medicine at the University of Texas's Southwestern medical centre in Dallas, made an overnight trip to London to make the plea before flying home.

"The question is how you determine who has the damage and who doesn't, and who needs to be cared for and maybe compensated. If we had an objective test that everyone agreed to then this would not be a difficult matter. We are developing biological understanding of that problem so that we can develop a reasonably inexpensive test you could apply to veterans."

Dr Haley's work was at first looked on with grave scepticism by the US government and other scientists, especially since effort was being concentrated on problems such as stress. But the billionaire businessman and former presidential candidate Ross Perot championed and funded his ground-breaking studies.

Dr Haley said some disease in veterans resembled early stages of well-known conditions such as Parkinson's.

Research by his team and others, he said, indicated that low-level sarin nerve gas, released by bombing attacks or post-war destruction of Iraqi factories and weapons stores, caused brain cell damage. In some cases, the agents may have acted in combination with pesticides or tablets taken as protection against nerve agents.

Troops particularly susceptible were those with low levels of a particular enzyme. "All it does is destroy nerve gas... Why did God put it there? I guess he knew the end of the story."

Among these troops, those under unseen clouds of sarin, particularly after raids early in the bombing war, were defenceless, he said. Similar damage had been seen in rats dosed with sarin by researchers in Albuquerque, New Mexico. As in veterans, signs of disease were delayed.

Dr Haley said many symptoms reported by many veterans were attributable to such damage. He believed there were three sets of Gulf-related cell damage - the worst linked to confusion, vertigo and dizzy spells, a second related to thinking problems, depression and sleep disorders, and a third to pain, although symptoms overlapped.

Dr Haley hoped Lord Lloyd's inquiry would push for work exploring brain cells in Britain. Scientists could find a way of reversing the damage.

Mr Perot made a similar plea. "As the US government seems to be getting its act together and taking steps to right the wrongs of the last decade, I am here to urge the British government to join with us to solve this problem.

"I urge you to retire the clique of stress researchers here in the UK who have only refused the issues, and start a new research funding initiative, this time supporting a new group of neuroscience researchers who can contribute constructively to our understanding of the problem."

home