Al-Qaeda nuclear plans confirmed

The documents are believed to belong to Bin Laden's network

The United States has confirmed that documents found in a Kabul building believed to have been used as a safe house by Osama Bin Laden's al-Qaeda network contained details about how to produce nuclear weapons.

US Homeland Security Director Tom Ridge said the information could have been found on the internet and it did not mean Bin Laden was able to build a nuclear device.

We have to be prepared for all eventualities, including a nuclear threat

Tom Ridge, US Homeland Security Director

"Much of that information could have been taken right off the internet some years ago. So there is nothing unusual about that information," said Mr Ridge.

It comes after Britain's Times newspaper said one of its reporters found the papers, which were partly burned, as the city was taken over by Northern Alliance fighters.

Mr Ridge said their discovery was consistent with statements made by Bin Laden - the main suspect in the 11 September suicide hijackings - that he wanted to acquire a nuclear capability.

The documents explained how to detonate explosives to compress plutonium and trigger a thermonuclear reaction.

They were in Arabic, German, Urdu and English.

Plans for poison

The documents are also said to have contained formulae for producing a lethal biological poison, ricin.

Bin Laden's claim that he has a nuclear bomb has been dismissed

Ricin, which is derived from a toxin protein in castor oil seed, was used to kill Bulgarian dissident Georgi Markov in London in 1978.

Nuclear experts quoted by The Times said that the design in the documents suggested that Bin Laden might have been working on a fission device, similar to the bomb dropped on Nagasaki in 1945.

However, the experts said, building a viable warhead was extremely difficult.

UK Defence Secretary Geoff Hoon dismissed a recent claim by Bin Laden to possess a nuclear bomb, but said that intelligence services did believe that al-Qaeda might have obtained nuclear material.

Such material is not hard to come by, the director of a Moscow think-tank has told the BBC.

Smuggling from Russia

In Russia, two men have been arrested for trying to sell cobalt-60, a radioactive material that can be used to carry out a radioactive terrorist attacks.

Cobalt 60 is widely used, not only in the military, but also in civilian industry

Ivan Savranchuk

Ivan Savranchuk, the director of the Centre for Defence Information, told the BBC that this was not the first case of people being arrested for attempting to smuggle or sell radioactive materials.

He said cobalt-60 could easily be obtained from the civilian industry, where it is used for medical engineering purposes.

He emphasized, however, that the material could not be used for making a nuclear bomb - but could be used on a smaller scale, with conventional weapons that could spread radioactivity.

Other documents found by the Times reporter included instructions on how to develop a "supergun" and build smaller bombs, the paper said.

"The documents lay strewn around the top floor, along with copies of aircraft magazines advertising flying instruction manuals, navigation instruments and flying charts," it said.