The head of the UN nuclear watchdog said on Monday his agency was looking into a report by a dissident Iranian group that it had evidence of a new, secret underground uranium enrichment site in Iran.
Director General Yukiya Amano suggested the International Atomic Energy Agency did not have complete information about the extent of Iran's nuclear programme. He urged Tehran to implement IAEA rules obliging it to inform the agency before it starts any construction work of a new facility.
"We are aware of this information (from Iranian dissidents) through media reports and we are now assessing this information. But at this stage we do not have anything more to share with you," Mr. Amano told a news conference in Vienna.
He said the IAEA had not received prior information from the dissident group about its assertions.
Exiled Iranian dissidents said last week the information came from a network of sources inside Iran affiliated with the exiled opposition National Council of Resistance of Iran (NCRI) and the People's Mujahideen Organization of Iran (PMOI), a guerrilla movement opposed to the Islamic Republic's government.
It said the site was intended as a facility to refine uranium deep under a mountain near Qazvin, about 120 km west of Tehran, and was about 85 per cent complete.
U.S. officials said on Thursday they have known about the facility for years and have no reason to believe it is nuclear.
Iran denied the dissidents' accusations. Its main enrichment plant is near the central city of Natanz. A year ago, Iran revealed the existence of a second plant being built inside a mountain bunker near Qom after keeping it secret for years.
While the NCRI in 2002 exposed Iran's uranium enrichment facility at Natanz and a heavy water facility at Arak, analysts say it has a mixed track record and a clear political agenda.
Uranium enrichment can produce fuel for nuclear power plants or, if taken to a higher level, for atomic bombs. Iran rejects Western accusations it is seeking to develop atom weapons, saying its work is aimed at generating electricity.