What is happening today?
The Observer reported at the weekend that compelling evidence that thousands of British troops who served during the Gulf war are dying prematurely and suffering debilitating illnesses because of exposure to a lethal cocktail of chemicals is to be put before a powerful commission of inquiry that is meeting today.

The US Congressional Subcommittee on National Security is holding an unprecedented meeting in Westminster, where it will reportedly be claimed that there is now enough evidence to make a direct link between serving in the Gulf and physical and mental disability.

What is believed to be causing the illness?
The Observer's political editor, Kamal Ahmed, reported that Shaun Rusling, chairman of the National Gulf Veterans' and Families Association (NGVFA), will reveal that tests on veterans have found traces of depleted and enriched uranium in their blood and urine. Depleted uranium was used by the Ministry of Defence (MoD) in 'tank-busting' missiles during the Gulf war.

Many of the men affected were involved in clean-up operations following Desert Storm in 1991. Illnesses among more than 5,000 British veterans will also be linked to powerful immunisation tablets given to soldiers to protect them from chemical attack, including anthrax, and the use of corrosive organophosphates to try to keep down disease.

Campaigners for Gulf veterans hope that the hearing by the US Congressional subcommittee, one of the most powerful investigative bodies in America, will put the government under enough pressure to order a public inquiry into the illnesses, which are sometimes described as gulf war syndrome, or post-traumatic stress disorder (PTSD). Ministry of Defence (MoD) doctors have denied in the past that there any Gulf war disease.

What are the symptoms?
The most common symptoms and illnesses cited as gulf war syndrome include severe fatigue, nausea, fevers, muscle and joint complaints, memory loss, mood swings including severe aggression, insomnia, swollen glands and headaches. The NGVFA claimed earlier this year that 70% of servicemen who have died since the 1991 conflict killed themselves. The organisation claims these suicides account for 380 out of a total of 537 deaths.

A typical scenario, NGVFA says, is that the stress and illness leads many sufferers to lose their jobs, their relationships deteriorate and they lose their homes and then eventually take their own lives.

The MoD says official statistics record just 97 suicides among Gulf veterans, which is slightly higher than the suicide rate in a similar group of soldiers who did not fight in the war. The NGVFA says some deaths that were recorded as accidental were actually suicides.

How many British service people were in the Gulf?
Around 53,000 British soldiers took part in the Desert Storm campaign, the international effort to liberate Kuwait following the invasion by Saddam Hussein's Iraq.

How many veterans have claims against the government over the illness?
Around 4,000 gulf war veterans have outstanding claims against the MoD for illnesses they believe were caused by their role in the conflict according to Tony Flint, a former chairman of the NGVFA.

Have claimants had any success?
Shaun Rusling, a veteran, won a landmark ruling recently when a War Pensions Agency tribunal officially recognised Gulf war syndrome as a disease. But many other veterans have been turned down for army pensions because the Ministry of Defence says there is no such disease.

Who will be at today's hearing?
Former US presidential candidate Ross Perot and three US Congressmen are hearing UK war veterans give evidence in parliament on Gulf war syndrome. The hearing is being hosted by the Royal British Legion and the UK Inter-Parliamentary Gulf War Group who want the British government to launch a public inquiry as a similar investigation into the syndrome to one which is ongoing in the US.

The MoD will be present at the Congressional hearings but only as observers. Yesterday Mr Perot, a Texan oil billionaire who has funded research into the illness, told a Westminster press conference the UK was under an "enormous obligation" to investigate the syndrome.

What evidence will be heard?
Statements will be made from 14 witnesses including Samantha Thompson, the widow of Gulf war veteran Nigel Thompson who died of motor neurone disease in January, and ex-RAF navigator John Nichol, who was shot down during the Gulf conflict. Experts will also give evidence on subjects including multiple vaccination, nerve gas, exposure to radioactive uranium and pesticides - all of which have been identified as potential causes of the syndrome.

Tomorrow the US representatives will give presentations to around 150 peers and MPs, outlining their views of the progress being made in the US to identify the causes of Gulf war illnesses.