Iran acknowledged on Sunday that it bought nuclear components on a shady black market amid mounting concern that the Islamic Republic may still be concealing sensitive nuclear research.
Disclosures by Abdul Qadeer Khan, the father of Pakistan's nuclear programme, have in recent weeks lifted the lid on the global trade in nuclear technology that could be used to make atomic bombs.
"We have bought some things from some dealers but we don't know what the source was or what country they came from," Iranian Foreign Ministry spokesman Hamid Reza Asefi told reporters.
"It happens that some of those (dealers) were from some sub-continent countries," Asefi added, stressing that Tehran had informed the International Atomic Energy Agency (IAEA) about the purchases.
Western diplomats in Vienna say Iran has given the IAEA the names of five European middlemen and six Pakistani scientists who helped Tehran acquire nuclear technology.
Diplomats also say the IAEA has found parts usable in advanced "P2" centrifuges to produce enriched uranium in Iran.
But, the discovery of P2 centrifuge parts has increased concern in Washington and the European Union that Iran may still be hiding aspects of its nuclear programme.
However, a senior Western diplomat in Tehran told Reuters on Sunday he did not expect major revelations about Iran.
However, he said Iran wants to retain a capacity to enrich uranium to keep the know-how, while the West was united in seeking to persuade them to give up the programme completely.
"Weapons of mass destruction and nuclear weapons have had no place in Iran's defence doctrine and will not have," spokesman Asefi said.
The IAEA is expected to release a report on its inspections in Iran in the coming week.