U.S. intelligence officials say there is no evidence that the al-Qaida terrorist network ever built a so-called "dirty bomb" - an explosive device that could spread deadly radioactive debris.
Intelligence officials say there is no doubt that al-Qaida members in Afghanistan had the ingredients to make a dirty bomb - explosives plus radioactive material, mainly taken from hospital x-ray machines.
But these officials, speaking to VOA on condition of anonymity, say that, while al-Qaida had the components, there is no evidence that the terrorist group ever actually manufactured such a device.
The officials say U.S. and coalition forces have scoured Afghanistan for evidence of any efforts by al-Qaida or its Taleban allies to develop weapons of mass destruction - that is chemical, biological and nuclear arms.
They say the search turned up what one official termed "the dirty stuff," which had been taken from hospitals, as well as evidence that terrorists bought additional materials they thought were radioactive.
But the official says the terrorists appear to have fallen prey to a scam associated with Russian organized crime circles, involving a phony material called "red mercury."
One year ago, U.S. officials said a shadowy Russian arms dealer might be linked to the sale of fake radiological material to al-Qaida.
The dealer was identified as Victor Bout, who analysts estimate earned some $50 million from arms sales to the Taleban in the late 1990s.
U.S. investigators also reported last year they found trace evidence of anthrax and another deadly poison called ricin at several suspected al-Qaida terrorist facilities in Afghanistan.
But they said there was no conclusive evidence that al-Qaida developed the capability to manufacture large quantities of anthrax or other chemical or biological weapons.