A UN spokesman said there was sufficient evidence to call for safety precautions when dealing with such locations.
Nato has denied that there is a health danger from DU, which is used in armour-piercing shells.
Click here to see where concerns have been reported
The alarm was raised this week when Italy, France, Belgium and Portugal called for an urgent investigation into cases of leukaemia among soldiers who had served in Bosnia and Kosovo.
Spanish concerns
The Spanish newspaper El Mundo reported on Saturday that "at least eight" former soldiers and aid workers were suffering from various cancers.
Spain officially denies that any Spanish soldiers were contaminated by radiation, despite the death of a former peacekeeper from leukaemia.
Belgium has now asked the Swedish Presidency of the EU to look into the matter, a Swedish Defence Ministry spokeswoman told BBC News Online.
Paula Burrau said the EU's political and security committee will debate the issue in Brussels on Tuesday.
Radioactive 'souvenirs'
A team of UN scientists from several different countries visited 11 out of 112 sites in Kosovo bombed by Nato.
You cannot totally exclude the possibility that people can sometimes suffer serious health effects from this type of ammunition
Head of UN mission, Pekka Haavisto
At eight of the sites, they found either remnants of DU or evidence of increased radioactivity around the impact points left by the raids.
The head of the team, Pekka Haavisto, told the BBC that 18 months after the Kosovo conflict they were surprised to find parts of DU weapons lying about in villages and graveyards where they could easily be picked up.
"It can happen that children are playing in those areas, they pick up some remnants."
"Even adults were picking up some memoirs of the war and putting them in their rooms - and then you have a radioactive source," he said.
Mine risk
The UN says it cannot draw full conclusions from its work until detailed analysis is completed, but has warned that precautions should be taken near the sites, by both civilians and military personnel.
Mr Haavisto pointed out that mine-clearance operations could expose people to serious health risks.
"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."
European Commission President Romano Prodi has said that, if there was a risk to either military personnel or civilians, then the weapons should be abolished.
Nato divided
Depleted uranium is only mildly radioactive but, on impact with a solid object, it burns off in a spray of fine dust, which some scientists believe can cause cancer.
However, the United States, Germany, the UK, Spain and Turkey, among other countries, say they have found no evidence of a link.
Pentagon spokesman Kenneth Bacon said the US military had carried out extensive studies into the use of the weapons during the Gulf War, and had found no evidence of a cancer or other health risk.
The UK Ministry of Defence also rejected suggestions of a link.
But other Nato allies are not so confident the weapons are safe.
Italy, France, Belgium, the Czech Republic and Portugal are all looking into the deaths of former peacekeepers and are urging further investigation of the issue.
Related to this story:
Pressure grows for uranium tests (06 Jan 01 | Sci/Tech) Nato reveals Kosovo depleted uranium use (22 Mar 00 | Sci/Tech)