Foiled: plot to devastate capital with a radioactive 'dirty bomb'

A plot to attack London with a radioactive "dirty bomb" was foiled by intelligence services, it emerged today.

Terrorists based overseas made detailed plans to smuggle a device into Britain and detonate it in the heart of the capital, to create panic and undermine the economy.

Their plot was foiled by an operation involving British, American and Pakistani intelligence agencies. Had it succeeded, the impact on London could have been devastating.

A dirty bomb is an improvised ex-plosive device wrapped with radioactive material, such as nuclear waste. It is designed to scatter deadly particles over a wide area, contaminating an area possibly for years, and causing fear of illnesses linked to exposure to radiation, such as cancer.

Former shadow security minister Patrick Mercer confirmed the existence of the abortive plot, which was kept secret. "I'm aware there was a plot to use a dirty bomb in London in 2004 that was foiled before the material got near the UK," he told the Evening Standard.

"This led to a great deal of work by the then government on resilience planning, and the plans to evacuate not just London but also other major cities." In the same year as the foiled plot, advisers drew up contingency plans to move Parliament to a secret location outside the capital. Plans to evacuate areas was prepared at least two years earlier by a "London resilience" committee.

London hospitals have been told to stockpile anti-radiation drugs since 2002, for distribution within hours of an attack. Potassium iodate in tablet form protects the thyroid, which is highly vulnerable to radiation.

New WikiLeaks revelations underline the threat posed by dirty bombs. Diplomatic files show al Qaeda is trying to secure nuclear material and rogue scientists to create a device. According to the classified US cables, a head of the International Atomic Energy Agency warned of a potential "nuclear 9/11" if extremists were to get hold of uranium and plutonium.