This is the post-war conclusion of the intelligence community, and the republican-led Senate Select Committe on Intelligence. The conclusions were virtually unaniously adopted by both republicans and democrats, 15-1.
US Senate Bipartisan Iraq Intelligence Report - Phase 2, Sept. 2006:
“In a response to questions from Committee staff asking if DIA recovered or received information or intelligence, after the raid on Salman Pak in April 2003 that indicated non-Iraqis received terrorist training at the Salman Pak facility, DIA said it has "no credible reports that non-Iraqis were trained to conduct or support transnational terrorist operations at Salman Pak after 1991." DIA assessed that the foreigners were likely volunteers who traveled to Iraq in the months before Operation Iraqi Freedom began to fight overtly alongside Iraqi military forces...DIA said it has "no information from Salman Pak that links al-Qa'ida with the former regime."….The facilities included a derelict aircraft and train intended for counterterrorism training.
In response to a question from Committee staff about postwar information recovered at Salman Pak, DIA said is has ”no information from Salman Pak that links al-Qa’ida with the former regime.”
http://www.fas.org/irp/congress/2006_rpt/srpt109-331.pdf