Fresh evidence has come to light of long-standing military concern about the potential health effects of depleted uranium (DU).

Documents obtained by the BBC suggest that the United States military was concerned about weapons containing DU even before the Gulf War, exactly 10 years ago.

US concerns

Health Environment Public reaction Report issued July 1990 Concerns dismissed after subsequent research

The revelations come as the medical chiefs of the Nato alliance meet in Brussels to assess the health scare, and a Portugese team in the Balkans reports that its initial inquiries have found no trace of the metal.

Scientists from Lisbon's Institute of Nuclear Technology searched for radioactivity at Portuguese-occupied barracks in Visoko, 30 kilometres from Sarajevo.

The head of the team, Fernando Carvalho, told Portugese television: "We were expecting to find some traces of it, but until now all the screening carried out on the soldiers and vehicles from these barracks has been negative."

Nato insists there is no evidence of a link between DU and higher incidences of cancer and leukaemia reported by troops who served in the Balkans.

Seven Italians, five Belgians, two Dutch nationals, two Spaniards, a Portuguese and a Czech national have died after serving in the Balkans. Four French soldiers have also contracted leukaemia, but the French defence ministry says they have tested negative for depleted uranium in their urine.

The World Health Organisation says "uncertainties remain", and several Nato member states have launched their own investigations into the matter.

Warning bells

The US Army expressed concern about the use of DU in July 1990, some six months before the outbreak of the Gulf War, where it was used in armour-piercing shells.

Nato targeted Yugoslav tanks with DU-tipped weapons

The BBC's defence correspondent Jonathan Marcus says significant concerns about health and environmental risks were included in the appendix of a report comparing the effectiveness of tungsten alloy and DU in armour-piercing ammunition.

The US report also suggested that the use of these weapons might cause public controversy.

A Pentagon spokesman dismissed the concerns, saying the report is 10 years old and that a lot of scientific work has been done since then.

Nato also denies DU causes health problems, but in the face of mounting public fears decided last week to set up a special committee to investigate the concerns raised in several European countries.

Inquiries

The committee is due to meet for the first time on Tuesday, after Nato members' medical officers exchange information on Monday.

Italy - following the deaths from leukaemia of at least seven of its Balkan veterans - has asked Nato to start an investigation.

Several other EU countries have already started their own inquiries, and the European Commission has set up a working group of medical and scientific experts that is due to report next month.

Last week, the German Government said it could not establish a link between possible DU contamination and a blood related illness suffered by six German soldiers.

But a study commissioned by the German Ministry of Defence warned that steps should be taken to prevent potential danger to the local population, particularly children, who may play in areas where DU weapons exploded, releasing toxic chemicals.