This interesting story comes from the informant Omar Nasiri, that the seizure of senior Al-Qaida officer Ibn Sheikh al-Libi, who was tortured in Egypt at the behest of the US in November 2001. According to Nasiri it was Libi who manufactured the story that Saddam Hussein had offered to train Al-Qaida in the use of chemical or biological weapons, which he repeated to his US interrogators. According to Nasiri, Libi was too well-trained to break under torture and clearly wanted the US to believe the story, which was of course, untrue. Still it was as Libi anticipated, seized upon by Colin Powell who repeated it as justification for the invasion of Iraq. According to Nasiri, this was thought of as a very cunning ploy by Al-Qaida to have dragged the US into Iraq, that they had already identified as the weakest of Arab states and prime territory for destabilisation.
The depressing thing in all of this is that even though the US would have invaded anyway, Al-Qaida thought it was a good thing if they did. That is because their interests are not synonymous with those of the Iraqis. On the contrary, they view them with contempt (as was clear in Zarqawi's hierarchical estimate of Kurds, Shia and Sunnis), cannon fodder for a war THAT THEY HAVE NO INTENTION OF WINNING.
Of course, this is not the first time that Al Qaida and its predecessors collaborated with imperialism. As late as 1993 Osama bin Laden was collaborating with the US over the deployment of the 'Afghan Arabs', veterans of the war with the Soviets against Serb forces in the former Yugoslavia. And in 1991, be it remembered, bin Laden's objection to the war against Saddam was not that it should be fought - on the contrary, he wanted it to be fought, alongside the US, only he objected to the siting of US troops in Saudi Arabia. That was when he approached the Sauds with a plan for an independent Arab battalion to defend the Kuwaiti autocrats against Iraq.