WASHINGTON, Nov 24: Al Qaeda is fully capable of building a radioactive "dirty bomb" targeting the United States and other Western nations and "has crude procedures" for producing chemical weapons, the CIA warned.

In an annual report to Congress on proliferation threats, the US Central Intelligence Agency also repeated on Tuesday its insistence that Iran was pursuing "a clandestine nuclear weapons program." But it remained silent about charges made earlier this month by Secretary of State Colin Powell, who accused Iran of seeking to adapt its missiles to carry nuclear warheads.

Instead, the agency used its strongest terms to alert lawmakers to the threat of terrorist organizations using chemical, biological, radiological and nuclear materials to harm the United States and its allies, saying the danger of such an attack "remained high."

The CIA said analysis of an Al-Qaeda document recovered in Afghanistan in 2002 "indicates the group has crude procedures for making mustard agent, sarin, and VX."

The network that masterminded the September 11, 2001 attack, intelligence officials said, could also attempt to build a cyanide-based chemical weapon capable of producing a lethal concentration of poisonous gases in an enclosed area.

In addition, Al-Qaeda is keenly interested in radiological dispersal devices, or "dirty bombs." Construction of such a device "is well within its capabilities as radiological materials are relatively easy to acquire from industrial or medical sources," the spy agency warned.

Documents recovered by US forces in Afghanistan show that Al-Qaeda founder Osama bin Laden and his associates were engaged in what intelligence officials described as "rudimentary nuclear research." But the CIA cautioned that the true extent of Al-Qaeda's nuclear programme "is unclear," suggesting it could be more advanced than originally thought. The intelligence agency said outside experts, citing as example the name of Pakistani nuclear engineer Bashir al Din Mahmood, may have provided assistance to the group in advancing its nuclear programme. -AFP