Four demonstrators then swam in the moat that surrounds the Abbey Wood compex at Filton to protest against the use of depleted uranium.

Despite a heavy police presence, the protestors managed to climb over the perimeter fence and into the top secret premises.

They made their point by swimming in the moat for more than five minutes. The police refused to get wet, allowing the protest to continue with no arrests.

The demonstrators say they targetted Abbey Wood because civil servants inside the building buy and supply weapons for the British military.

Protester Margaret Jones of Direct Action against Militarism and Depleted Uranium said: "The point of the protest was to highlight the fact that this lovely building does all the buying for the military, including radiocative weapons and depleted uranium which has caused our own troops to get sick and has caused defects and deformities in the Balkans and in Iraq.

"It also does the purchasing for the Trident Nuclear missile system and our taxes pay for all this."

Dave Rolestone from Voices in the Wilderness said: "We're highlighting that this place is the procurement centre for all those bombs that dropped on Iraq - this is costing the British taxpayer £4m a month.

"I've been there three times and seen the devastation there. Four to 6,000 children die there every month.

"There are hundreds of British troops that are affected by depleted uranium. It will still be operating in 4.5bn years - that's longer than the sun is expected to last and so the radiation from that will affect makind from now to eternity."

Ray Davies of CND Wales said: "Depleted uranium is causing death and destruction wherever it goes, even to our own soldiers and that's why we're here. This is one of the main places in the UK and we want to highlight that this place is dealing in death and destruction to millions of people all over the world."