Commandant Frank Cop is an angry man and a formidable opponent. A soldier in the Belgian army for 30 years, his career was cut short by illness two months after returning from duty as a peace monitor with the UN and the EU during the Bosnian war.

In five years, says Cop, aged 50, he has been beset by a series of devastating ailments. He suffers headaches and muscle aches, debilitating lethargy and skin complaints so serious he finds it uncomfortable to bathe. Blood tests recorded abnormally high levels of white cells. Invalided out of the armed forces on a reduced pension, Cop embarked on a one-man campaign on behalf of Belgian veterans of the Balkans: victims, he claims, of a mysterious 'Balkans Syndrome', similar in its symptoms to the Gulf war Syndrome claimed by veterans of the war against Iraq.

Cop is convinced he knows what has made him ill. He believes he was contaminated by the highly toxic residue from the three tonnes of depleted uranium (DU) ammunition fired by US aircraft against the Serbs during the Bosnian war.

Last week Cop - one of the first peacekeepers to claim he was suffering from Balkans Syndrome - found himself at the centre of one of Nato's biggest peacetime crises, a scandal gripping the armed forces of a dozen European countries, as military chiefs across a continent ordered urgent checks on the health of soldiers allegedly exposed to depleted uranium in the Balkans.

A week after the announcement by the Italian Defence Ministry that it was investigating the deaths from leukaemia of six of its Kosovo peacekeepers for links to depleted uranium, scores of former Balkans peacekeepers - from Hull to Lisbon - are now claiming they are suffering from unexplained ailments, as the media from Rome to Berlin has daily turned up new cases of peacekeepers who died from cancers after returning from the Balkans.

In Britain two former peacekeepers have come forward, including former Royal Engineer Kevin Rudland, who believes he was contaminated servicing tank guns while based in the Bosnian Serb town of Banja Luka. His symptoms are ones that Cop would recognise immediately, most prominent among them chronic fatigue.

'After I became ill in August 1996 I was referred to the military medical services,' Cop said last week. 'My white blood cell count was three times what it should be. The military doctors said I was ill, but they did not know what from.

'That is when I began investigating for myself. I got in contact with a German doctor who had been studying the effects of depleted uranium in the Gulf and he told me American forces had used depleted uranium ammunition during the Bosnian war. The Americans denied it. Now they admit it's true.'

In seven days the safety of the depleted uranium ammunition has become an international controversy, attracting competing charges of a US cover-up over the danger the ammunition poses and dangerous claims of 'scaremongering'. After a decade of inconclusive research had mostly ruled out any link between depleted uranium ammunition and cancers - and counter-claims alleging that it had caused thousands of cancers among Iraqi children - investigations into the health implications are suddenly under way in Belgium, Italy, France and Turkey; in Finland, Sweden, Portugal and Spain.

Among those who have demanded an investigation are Italy's Prime Minister Giuliano Amato who has called for a US moratorium on the use of depleted uranium shells - rejected by the Pentagon - and EU Commission President Romano Prodi who called for the banning of the ammunition if even the slightest risk was identified.

In response, Nato's Secretary-General Lord Robertson has promised the Italians to provide information on its use of the ammunition in the Balkans. Nato too will also discuss its safety at this week's meeting of Ministers.

It is a scandal that threatens to take high profile victims.

In Portugal the strength of feeling is so strong that it threatens to overshadow the presidential elections after the media reported claims that a Portuguese peacekeeper in Kosovo had died from ammunition poisoning.

As more alleged victims emerged in Portugal, a heated emergency parliamentary debate saw MPs angrily calling for the withdrawal of Portuguese troops from the region, accusing the government of withholding information from them after the military claimed the soldier had died from septicaemia. In Kosovo, the claims have sparked a panic over fears among moderate Kosovar leaders that the scandal may lead to the withdrawal of peacekeeping contingents.  In Britain, almost alone, the Ministry of Defence remains unmoved by the sense of panic gripping its European allies.

The MoD's radiation and health experts, in step with the Pentagon, insist debris of depleted uranium poses little risk to the health of servicemen. They will read new research, they say, with interest and an open mind, but reject any calls for their own health screening of Balkan peacekeepers.

Their hopes that the row might defuse, however, were shattered on Friday with the announcement by a UN Environment Programme task force that it had found evidence of 'radioactive contamination' at eight of 11 sites tested in Kosovo that were struck by depleted uranium ammunition during the war in 1999.

It is a disclosure, however, that still does not answer a question that has become the centre of heated scientific debate - whether the reassurances of the British and American defence chiefs over the safety of depleted uranium can be sustained. Or whether they have seriously underestimated its danger.

One organisation, at least is unconvinced, by their reassurances. On Friday the UN High Commissioner for Refugees confirmed its policy was to warn all staff travelling to Kosovo - and pregnant women in particular - of the potential risks of exposure to debris from depleted uranium still in the province.

The answer to the question of whether depleted uranium ammunition is really safe may not lie in the bomb craters of Kosovo and Serbia. Instead, some experts believe, it is likely to be found in an area of barren Iraqi desert near the border with Kuwait, a place littered with remains of the last great land battle of the twentieth century - Operation Desert Storm.  It was here that depleted uranium ammunition was used for the first time - more than 30 metric tonnes - 300,000 rounds in all.

It is a landscape still dotted with the ruins of Iraqi tanks blasted with the ammunition, the rents in their armour still emitting tell-tale signs of low-level radiation.

Significantly this battlefield represents an unintentional experiment - a decade in the making - over what happens to depleted uranium debris in the environment and how it affects the health of local populations. The most serious of those effects, the Iraqi authorities have long claimed, has been a sharp rise in childhood leukaemias and birth defects.  And it was to here that British low-level radiation specialist Dr Chris Busby travelled three months ago to perform a radiological survey for an Arab television station. What Busby discovered surprised him. Soil samples - confiscated by the Iraqi authorities - showed lower levels of contamination than he expected.

But his air samples revealed levels of ionising radiation in the atmosphere around the battlefield 10 times higher than in the neighbouring city of Basra and 20 times higher than in Baghdad.  If his samples are correct, then US and British military claims that microscopic breathable particles of depleted uranium quickly disperse might not be true. It is this that is at the centre of the present controversy.

What is accepted by all sides is that when depleted uranium ammunition - used in bullets for its hardness and penetrating power - hits its target, it also explodes and burns at temperatures of up to 10,000 C forming a smoke or 'aerosol' of suspended particles composed of three toxic and radioactive compounds of uranium.

But, according to US and British defence experts, the only risk is to those in the vicinity of the battlefield in the immediate aftermath of the attack who breathe in concentrations of the aerosol of compounds.

The risk, they claim decreases, as the aerosol disperses to levels of risk below that acceptable within the civil nuclear industry. According to these calculations there should be no contamination of Iraq's air and little risk.

Busby, however, believes that the MoD's experts have got it wrong on two counts: on the way that charged, contaminated particles remain in the environment and - more seriously - over their risk models which he claims are outdated and underestimate the health impact by up to 1,000-fold, a claim he made in a paper to the Royal Society's Depleted Uranium working group last year.

Busby is not alone in believing the MoD may have got it wrong. Professor Malcolm Hooper, a member of the British Legion's Gulf War Illnesses Inter-Parliamentary group, also believes the advice given by health experts of the British and US military is dangerously out of date.  'New research suggests the risk threshold from inhaled particles is much, much lower than previously assumed,' he said.

Hooper points to research suggesting that genetic mutation to irradiated cell tissue takes place in a more pernicious way than previously assumed, with 35 per cent of cells neighbouring a single irradiated one showing evidence of damage.

The most controversial piece of research, however, has been undertaken in Newfoundland, Canada, where scientists at the International Uranium Centre tested the urine of British, US and Canadian Gulf war veterans, as well as that of Iraqi veterans and civilians, using for the first time Thermal Ionising Mass Spectrometry. They detected traces of depleted uranium in their urine.

The Ministry of Defence is sceptical about the work of both Busby and the International Uranium Centre, led by Professor Asaf Durakovic and Dr Patricia Horan, pointing instead to a US study by the Baltimore Veteran Affairs department of 33 American veterans who survived so-called 'friendly fire' incidents involving depleted uranium ammunition. 'These people have considerable amounts of depleted uranium in their bodies in the form of shrapnel, and excrete high levels of uranium in their urine,' said an MoD source. 'Significantly none of them of has shown significant problems, nor have their children.'

Frank Cop and the other victims are not going to be convinced.

• Additional reporting by Emma Daly in Madrid and Eduardo Goncalves in Lisbon
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