The tungsten penetrator provides improved round effectiveness while eliminating safety and environmental problems associated with DU

American Naval Sea Systems Command history

A Ministry of Defence (MoD) spokesman confirmed that the Americans' decision to cease manufacturing the naval DU munitions meant the Royal Navy had no choice but to phase them out.

The move came as it was revealed that a leaked Pentagon document from 1993, obtained by the BBC's Ten O'Clock News, warned of the potential increase in cancer risk after exposure to DU ammunition.

But the MoD spokesman insisted the decision had already been made as the tungsten alternative had been demonstrated to be as effective as the DU munitions.

The spokesman said he did not know whether there was a tungsten-based alternative to the DU tank-busting shells used by the Army.

Shells could be withdrawn

The Royal Navy's stocks of DU ammunition will be exhausted by 2003, although the shells may well be withdrawn before then.

The US Navy has been phasing out DU for a decade and it is believed the ammunition has been replaced totally by tungsten.

A report in the Times newspaper quotes an American Naval Sea Systems Command history written in 1989 as saying: "The tungsten penetrator provides improved round effectiveness while eliminating safety and environmental problems associated with DU."

The paper said the British phase-out had already begun, but the ships still carrying DU rounds are the aircraft carrier HMS Ark Royal, the 11 Type 42 destroyers, HMS Ocean, a new helicopter carrier, and HMS Fearless, the amphibious assault ship.

When soldiers inhale or ingest DU dust they incur a potential increase in cancer risk ... that increase can be quantified in terms of projected days of life loss

Leaked 1993 document US Army Surgeon General's office

Nato and the World Health Organisation have said there is no evidence of a link to cancer but the leaked 1993 Pentagon document, drawn up by the US Army Surgeon General's office after the Gulf War, suggests the US military knew otherwise.

It said: "When soldiers inhale or ingest DU dust they incur a potential increase in cancer risk ... that increase can be quantified in terms of projected days of life lost."

Early warnings

Opponents to DU's use by the Army continue to assert that indications to the government of the dangers date back as far as a warning to the US, a close Nato ally, in 1990.

An early 1990s British warning came from an official at AEA Technology, the trading name of the UK Atomic Energy Authority, in a document looking at what might happen if all the DU fired in the Gulf War by tanks - about 8% of the total DU used there - were inhaled.

If that happened, it said, the latest International Commission on Radiological Protection risk factors calculated there could be half a million deaths as a result by 2000.

The MoD knew there were some risks associated with DU as long ago as 1979.

An estimated 300 tonnes of DU were fired in the Gulf War

A spokesman told BBC News Online: "An MoD memo then was clear about both the toxic and the radioactive risks.

"We warned UK troops in the Gulf in 1991 about them, and since 1993 we have publicised our understanding of the risks.

"We've known for over 20 years that there are risks. But we don't think those risks are significant."

Meanwhile, Defence Secretary Geoff Hoon has said he would consider demands for the independent screening, as opposed to the proposed MoD testing, of British veterans who feared contact with depleted uranium (DU) weapons had made them ill.