In March 1991, a chemical weapons site at Khamisiyah was destroyed, creating a large plume of deadly smoke which may have drifted over more than 100,000 allied soldiers.

Australian sailors aboard vessels in the Persian Gulf may have been exposed to low levels of the nerve agent, which causes long-term damage to the nervous system and brain.

A report in New Scientist magazine speculates the various alarms used to detect chemical weapons were disregarded. In 1994, the US Defence Department estimated the 14,000 alarms around the troops went off two to three times a day, a total of between one to two million times. Even in low doses, sarin gas can cause serious damage.

Philip Steele of the Australian Gulf War Veterans' Association said the chemical alarms aboard HMAS Sydney went off so frequently they were turned off.

About 1800 Australians suffer from what they claim is Gulf War syndrome.

Mr Steele, who is on a totally and permanently incapacitated pension, said he took the anti-nerve agent drug pyridostigmine. Researchers say the drug can sometimes damage the body in the same way nerve agents do.

Australia and Britain deny there is such a medical condition as Gulf War syndrome, whose victims complain of a range of ailments, including anxiety, cognitive problems, arthritis, nausea, fatigue and sexual problems.

But now, the US looks as if it might be taking a different approach, based on new research.

There has also been speculation that injections given to allied troops before the war may have been behind the syndrome.

A recent Australian inquiry found Gulf War veterans appeared to suffer more from psychological than physical problems.