LONDON (Reuters) - The leak of a secret British Defense Ministry report warning that exposure to uranium-coated ammunition increased the risk of cancer added fuel Thursday to a worldwide debate about the safety of the weaponry.

A Ministry of Defense (MoD) spokesman confirmed that such a report had been prepared four years ago but dismissed it as flawed, written by a trainee and only a draft paper.

Britain, along with NATO and the United States, insists there is no evidence of a link between the use of depleted uranium (DU) weapons and cases of leukemia in troops who have served in the Balkans.

But the mere existence of the report heightened fears about the safety of DU ammunition used by British, U.S. and other western armies in the Gulf War and Balkans campaign.

NATO agreed Wednesday to a "robust" action plan to look into the effects of the so-called "Balkans Syndrome" but stuck to its statement that it posed a minimal health risk.

A day earlier, the British government essayed an abrupt policy U-turn, agreeing to test soldiers for possible health problems while insisting there was no evidence of a link.

The screening will be offered to Balkans peacekeepers, not Gulf War veterans. Similar weapons were used there and many who fought in the 1991 war against Iraq complain of serious illness.

Shaun Rusling, chairman of the National Gulf War Veterans and Families Association, said his members had lost any faith in the government.

"They are now trying to rubbish their own medical documents and safety procedures," he said. "There should be a public inquiry. We have got 521 Gulf War veterans who have died since April 1991. Many of them have died of cancers."

British media, who received the leaked army medical report, said it warned that inhalation of dust from DU led to accumulation in the lungs "with very slow clearance -- if any."

"All personnel should be aware that uranium dust inhalation carries a long term risk...the (dust) has been shown to increase the risks of developing lung, lymph and brain cancers," they quoted it as saying.

OFFICIALS DISMISS REPORT

The MoD spokesman told Reuters the report was scientifically incorrect. "It is flawed. It was done by a trainee. It was never endorsed by senior staff. It was not taken forward," he said. Defense ministers would not comment early Thursday but the MoD's chief scientific adviser went on BBC radio to give the report two marks out of 10 for accuracy and validity. "I have to say, rather cruelly, that the word flawed is correct. There are many, many scientific inaccuracies. It hasn't been scientifically approved," Keith O'Nions said.

Opposition Conservatives demanded to know if British ministers had known of the report and kept quiet about it.

But O'Nions, who advises ministers on issues like this, said: "The advice that ministers have had from myself and other scientific sources have never involved this document at all."

NATO has appeared split between the likes of Britain and the United States, who argue there is no health risk from DU, and Germany, Italy, Portugal and Belgium who want a full inquiry.