By BURT HERMAN, Associated Press Writer

BERLIN (AP) - NATO (news - web sites) warned countries with armies and aid workers in the Balkans about the possible dangers of depleted uranium ammunition, the German Defense Ministry said Sunday, an issue which has recently sparked concern as a possible cause of serious illnesses in soldiers who served there.

The ministry confirmed that it received a warning in July 1999 of the risks from the ordnance, used by the United States during air campaigns across Yugoslavia for its armor-piercing qualities.

According to an internal Defense Ministry document obtained by the Berliner Morgenpost newspaper and dated July 16, 1999, NATO had warned soldiers and aid workers that month of a ``possible toxic threat'' and advised them to take ``preventative measures.''

The ministry has previously said it began health checks on soldiers who had come into possible contact with the depleted uranium ammunition that same month - as U.N. peacekeeping forces were still entering Yugoslavia's Kosovo province after NATO's 78-day bombing campaign.

Despite that, the document said NATO planned no further steps, according to the newspaper. The Defense Ministry said it immediately responded with orders for soldiers on how to behave in areas that were targeted with depleted uranium.

The renewed concerns over depleted uranium arose in December after Italy announced an investigation into 30 sick soldiers who served in the region. Twelve have cancer and five have died of leukemia.

Since then, numerous other countries with troops in the Balkans have launched testing programs.

The United States has denied there are any health risks from the ammunition.

German Defense Minister Rudolf Scharping also repeated the ministry's assertion that the ammunition poses no danger. He is to present a report to parliament on the issue this month.

``All the facts should be on the table - but only facts,'' he told the Bild newspaper in an article to be published Monday.

Chancellor Gerhard Schroeder, on a visit to Russia, said the questions were serious ones and would be investigated.

``It is in our interests to see any danger to our own soldiers and those of our partners to be ruled out,'' he said. ``We want to have a clear picture first of what happened.''

President Vladimir Putin (news - web sites) of Russia, which had opposed the NATO bombing, on Sunday called the use of force in Yugoslavia ``impermissible'' and said investigations would have to determine ``why such weapons were used and with what results.''

Across Europe, the calls continued for a more thorough look into the possible effects.

``If it is shown that depleted uranium causes an increase in cancers, then we have got to look at alternative weapon systems and at precautions which could be taken to protect our troops, as well as at how we can clean up the areas where the shells were used,'' said Bruce George, chairman of the Defense Committee in Britain's House of Commons.

The British Defense Ministry acknowledged late Saturday that depleted uranium has been used at two firing ranges within Britain for more than 10 years, but said there was no evidence it posed a significant health or environmental risk.

Meanwhile, the head of the U.N. Environment Program criticized NATO for not being more forthcoming about where it used the ammunition. Klaus Toepfer told the Berliner Zeitung in an article to be published Monday that the alliance had taken the stance ``that investigation at these locations wasn't necessary anymore. That is very clearly not correct.''

UNEP has visited 11 of 112 sites in Kosovo identified by NATO as having been targeted with ordnance containing depleted uranium, and found higher radiation levels in eight locations. Final results are expected in March.

Toepfer said similar investigations should be done in Bosnia and Serbia, and that it was NATO's responsibility to dispose of the ammunition.

In Greece, the scare has rekindled public opposition to NATO's intervention in the Balkans - sentiment that spurred daily and sometimes violent street protests during the bombing.

Defense Minister Akis Tsochadzopoulos rejected calls to withdraw the country's 1,500 peacekeepers, saying Sunday that ``the soldiers did not go there on an excursion, they went to help bring stability to the region.''

Greece's military is planning to screen up to 4,000 current and former peacekeepers and has confirmed that a sergeant who served in Bosnia has leukemia.

Swiss authorities also said Sunday they would screen 900 soldiers who served in the Balkans for signs of radiation poisoning.

Meanwhile, Polish and Bulgarian officials said Sunday that tests so far on troops serving in Kosovo had shown no negative effects from the ammunition.