The controversy over the reported dangers of depleted uranium (DU) has intensified, with a Canadian study said to show "unequivocal" evidence of damage to health.

DU is a by-product of military and civil nuclear programmes, and is mildly radioactive, much less so than natural uranium.

Because it is 1.7 times as dense as lead, it is prized for use in armour-piercing weapons.

A DU round bursts through armour far more easily than a conventional weapon. On impact, the DU dissolves in a burning spray of dust.

Damage to children

The dust can damage health if it is inhaled or ingested. But the Ministry of Defence and the Pentagon have insisted that DU munitions, which both countries used in 1991, pose no special dangers.

Some Gulf war veterans disagree, and believe DU may be a factor in Gulf War Syndrome, the cluster of illnesses which has ruined the health of thousands of them.

They point as well to the much higher rate of childhood cancers and other abnormalities in southern Iraq since 1991.

And children of veterans themselves have been reported with birth defects.

DU weapons were also used in Kosovo

Research by Dr Hari Sharma, of the University of Waterloo in Ontario, appeared to show traces of DU in the urine of 14 out of 30 British veterans he tested.

There is now considerable dispute over his work, with critics claiming he was dismissed by the university for work that lacked rigour and credibility.

His supporters say he has been victimised for publishing evidence suggesting DU harms both veterans and civilians.

But research at the Memorial University of Newfoundland appears to support Dr Sharma.

The researcher, a geochemist, Patricia Horan, used a mass spectrometer to analyse the urine of veterans.

This technique is said to achieve results between 50,000 and 500,000 times more accurate than Dr Sharma's.

'Beyond argument'

The one British veteran to have received the results of his test, Shaun Rusling, of the National Gulf War Veterans' and Families Association, was shown to be still passing DU in his urine eight years after the war.

Malcolm Hooper, emeritus professor of medicinal chemistry at the University of Sunderland, says the new research provides "unequivocal evidence that will stand up to technical examination by anyone".

Professor Hooper, who advises Gulf veterans' groups, told BBC News Online: "This puts the whole thing beyond dispute. It is a breakthrough."

Arming for a sortie: DU gets results

"It shows an initial, significant exposure to DU, exposure which the MoD and the Pentagon have always maintained did not happen.

"It is imperative that the UK government now launches a widespread study of thousands of those who served in the Gulf, in different jobs and locations.

"US forces used DU in Kosovo, and that is disturbing as well.

"The climate and the terrain are different, but we just don't know what happened.

"The government should be checking service people, civilians, journalists, everyone."

Cautious

But the Newfoundland research has not yet been peer-reviewed, which worries Tony Duff, secretary of the Gulf Veterans' Association.

He told BBC News Online: "I think it is interesting. But until it has been reviewed, we cannot draw any firm conclusions.