The chief of the UN nuclear watchdog, Mohamed ElBaradei, admitted on Thursday that consultations with Iran on its nuclear issue reached a deadlock.

ElBaradei, director general of the International Atomic Energy Agency (IAEA), voiced "regret" that Iran had not responded to the agency's proposal of shipping its low-enriched uranium (LEU) abroad for further purification.

He said Iran's agreement to this proposal would help the international community to rebuild confidence in Tehran over the nuclear issue. It is regrettable that this opportunity was not seized by Iran, he said at the IAEA Board of Governors' meeting in Vienna.

ElBaradei added that this deadlock would be unable to break unless Iran engages fully with the UN agency.

With regard to the issue of the newly discovered nuclear plant in Qom, ElBaradei said the facility was "under construction" with about 3,000 centrifuges to produce enriched uranium.

"Iran failed to notify the agency of the existence of this facility," which violated the terms of the relevant nuclear safeguards, ElBaradei said.

The building of the uranium enrichment plant in Qom damaged Iran's credibility, he said.