The CIA published an article in 2013 titled Iraqi Human Intelligence Collection on Iran’s Nuclear
Weapons Program, 1980–2003. The piece demonstrates that much Iraqi intel was bad, but it’s worth a look at its accounts of Iran’s interactions with foreign entities.

FWIW, the 2007 NIE assessed “with low confidence that Iran probably has imported at least some weapons-usable fissile material,.” And former DCI John Deutch testified in 1996 that “Iran has launched a parallel effort to purchase fissile material, mainly from sources in the former Soviet Union.:”

• Iranian agents have contacted officials at nuclear facilities in Kazakhstan on several occasions, attempting to acquire nuclear-related materials. For example, in 1992, Iran unsuccessfully approached the Ulba Metallurgical Plant to obtain enriched uranium. 
• In 1993, three Iranians believed to have had connections to Iran’s intelligence service, were arrested in Turkey while seeking to acquire nuclear material from smugglers from the former Soviet Union.