But the Ministry of Defence (MoD) has insisted the risks to personnel were minimal.
The UN Environment Programme (Unep), based in Geneva, said that its preliminary findings, at the sites hit by Nato ammunition, called for precautions to be taken when dealing with such locations.
But the Ministry of Defence (MoD) has insisted the risks to personnel were minimal.
It has said so far there are no plans to test British troops who served in Bosnia and Kosovo, although it said it was waiting to see the outcomes of tests being carried out by other nations and the UK's Royal Society.
But Liberal Democrat defence spokesman Menzies Campbell said the findings raised concerns.
He said: "The use of depleted uranium shells has long been controversial and we owe it to the men and women of our armed forces to take every precaution for their protection.
"Nor can we shirk our moral and legal responsibility not to use a weapon which may have devastating consequences for civilians long after the conflict has ended."
'Balkan war syndrome'
Nato has also denied that there is a health danger from depleted uranium, which is used in armour-piercing shells.
A team of UN scientists from several different countries visited 11 out of 112 Nato bombing sites in Kosovo.
The UN said on Saturday that analysis of the DU collected in Kosovo to determine if there was any health or environmental risk was continuing.
DU is a heavy substance, 1.7 times as dense as lead, and used in armour-piercing munitions.
Exposure to the uranium has led to the emergence of a "Balkan War syndrome", some servicemen claim.
Former British Army engineer Kevin Rudland has said his medical condition and the deaths of six Italian soldiers may be linked to the use of DU in cannon shells fired during the air strikes of 1999.
Within a few months of his return in 1999, Mr Rudland's hair fell out, he began to suffer from post-traumatic stress disorder, his teeth started to rot and he suffered from osteoarthritis.
His symptoms have not improved since, and he now sees a psychiatrist for psychological problems caused by his illness, which he said had made him "unemployable".
He said: "These UN findings do not surprise me. This is what we are trying to get over to the government.
"They should screen British soldiers to find out if they were contaminated,
so it can be sorted out, if they were.
"Civilian doctors don't know the symptoms we are suffering from - they don't recognise them."
The UN says it cannot draw full conclusions from its work until detail analytical work is completed, but has warned that precautions should be taken near the sites, both for civilians and military personnel.
The head of Unep's Balkan DU assessment team, Pekka Haavisto, told the BBC that a year-and-a-half after the conflict they were surprised to find parts of DU weapons lying about in villages and graveyards where they could easily be picked up by children and adults.
Mine-clearance operations could expose people to serious health risks, he said.
"If you explode mines in the areas where there is DU ammunition in the ground, you probably also explode again some DU ammunition and inhale this type of dust. So you cannot totally exclude the possibility that people can sometimes suffer serious health effects from this type of ammunition."
Further investigation
The samples taken are being analysed in Sweden, Switzerland, Britain, Austria and Italy, and Unep expects to have the results in early March.
It has also said it is planning a field mission to Serbia and Montenegro.
The European Union has announced it will conduct an inquiry into possible health risks from the ammunition.
Italy, France, Belgium, the Czech Republic and Portugal are some of the countries looking into the deaths of former peacekeepers and are urging further investigation into the issue.
But the MoD and the US Defence Department both say there is no evidence of any link between depleted uranium and illness or death.
A MoD spokesman said: "We are unaware of anything that shows depleted uranium has caused any ill health or death of people who served in Kosovo or Bosnia."