Al-Qaeda is attempting to procure nuclear material and recruit rogue scientists in order to build a radioactive "dirty bomb," leaked documents published in Wednesday's Telegraph newspaper revealed.

The cables, released by the WikiLeaks website, showed that security chiefs told a Nato meeting in January 2009 that Al-Qaeda was planning a programme of "dirty radioactive improvised explosive devices (IEDs)."

The makeshift nuclear bombs, which could be used against soldiers fighting in Afghanistan, would contaminate the surrounding area for years to come.

The leaked documents also revealed that Al-Qaeda papers found in 2007 convinced security officials that "greater advances" had been made in bio-terrorism than was previously feared.

US security personnel were warned in 2008 that terrorists had "the technical competence to manufacture an explosive device beyond a mere dirty bomb."

Also laid bare in the diplomatic cables are the attempts made to smuggle volatile materials as rogue organisations seek to get their hands on weapons-grade fuel.

The memos detailed how a freight train on the Kazakhstan-Russia border was found to be carrying weapons-grade material while a "small-time" dealer in Lisbon tried to sell radioactive plates stolen from Chernobyl.

In a separate leaked memo, which documented a January 2010 meeting between Janet Napolitano, US Secretary of Homeland Security, and European ministers, the German interior minister revealed his concerns over aircraft security.

According to the cable, Thomas de Maiziere expressed his fear that terrorists could use "children's articles to introduce bombs into airplanes."