VIEANNA; Four inspectors of the UN International Atomic Energy Agency were leaving Vienna today for Tehran to visit Iran’s controversial second uranium enrichment plant, an agency spokesman said.

“They have gone through security and their plane should take off around 3:00 pm (1300 GMT), Dana Sacchetti told AFP.

They are due to visit the site near the holy city of Qom on Sunday, two days after Tehran postponed its response to a UN deal on supplying the Islamic republic with nuclear fuel.

Media reports said the team will spend three days in the country to inspect the facility being built inside a mountain some 100 km south of the capital.

Tehran’s disclosure of the

new plant to the IAEA on September 21 triggered widespread

global outrage, with US President Barack Obama warning Iran

would face “increased pressure” if it does not come clean on its nuclear activities.

IAEA chief Mohamed ElBaradei criticised Tehran for what he said was its late disclosure of the facility’s existence.

Uranium enrichment lies at the heart of Western concerns about Iran’s nuclear programme. It produces fuel for civilian reactors, but in highly extended form can also make the fissile core of an atomic weapon. Western powers led by Washington suspect Tehran is enriching uranium with the ultimate aim of making the bomb, a charge Iran strongly denies.

Iran has been enriching uranium at a separate facility in Natanz for several years in defiance of three sets of UN sanctions.

Officials claim that new generation centrifuges — the devices which spin at supersonic speed to enrich uranium — would be installed at Qom.

The inspection has gained further significance after Tehran delayed on Friday its response to an IAEA deal under which Iran would ship its existing stock of low-enriched uranium (LEU) to Russia.

World powers are concerned that the material, if not shipped out, could be further enriched in-house by Iran to weapons grade.