TEHRAN: UN experts will visit a controversial uranium enrichment plant south of Tehran on Thursday, as US President Barack Obama warned of "consequences" after Iran dismissed a UN-brokered nuclear fuel deal.

The visit by the International Atomic Energy Agency (IAEA) team to the plant, which is being built inside a mountain near the Shiite holy city of Qom, was announced on Wednesday by Iran's envoy to the IAEA, Ali Asghar Soltanieh.

"It is a routine visit," a source close to Iran's nuclear body told AFP about the inspection, which is the second by the IAEA in less than a month.

Four inspectors first visited the plant on October 25 after its disclosure by Iran to the agency triggered intense outrage in the West.

"This site will, from now on, be under the IAEA. And for your information there will be tomorrow another inspection of this site in order to make sure that we are fully cooperating," Soltanieh told reporters in Vienna on Wednesday.

The Fordo plant, named after a nearby village where large numbers ofIranians were killed during the war with Iraq in the 1980s, is guarded by anti-aircraft guns.

Iranian officials say the construction of the plant is a message to the West that Tehran will never give up its uranium enrichment work and that the plant is a back-up facility in case the main enrichment plant at Natanz is bombed.

Washington and arch-foe Israel have never ruled out a military strike against Iran's nuclear facilities which they suspect are being used to make weapons, a charge strongly denied by the Islamic republic.

Soltanieh has said that Iran has no other enrichment plants apart from Fordo and Natanz.

The UN inspection comes a day after Iran rejected plans for it to send more than 70 percent of its stocks of low-enriched uranium (LEU) abroad under the IAEA-brokered deal.

Foreign Minister Manouchehr Mottaki said on Wednesday that Iran is however ready for more talks with world powers on the issue and is prepared to consider the idea of a simultaneous exchange of uranium for fuel for a Tehran reactor.

The IAEA however has already said that idea is unacceptable to the Western powers, who support the UN-brokered deal because they believe it would leave Iran with not enough stocks of LEU to be able to make a bomb.

Obama stepped up pressure on Iran after the Islamic republic dismissed the fuel deal.

He warned Washington has "begun discussions with its international partners about the importance of having consequences."

"Our expectations are that over the next several weeks we will be developing a package of potential steps that we could take that will indicate our seriousness to Iran."

World powers have warned Iran that it could face tough new sanctions if it rejects the deal.

Mottaki, however, scoffed at Western threats of punishment.

"Sanctions was the literature of the '60s and the '70s," Mottaki said in Manila on Thursday.

"Well, in the last four years they have the experience of doing so. And I think they are wise enough not to repeat failed experiences. Of course it's totally up to them."

The Obama administration was initially optimistic that Tehran would accept the IAEA deal which emerged from talks between Iran and Russia, China, the United States, Britain, France and Germany.

Under the IAEA-brokered proposals, Iran would send out 1,200 kilograms (more than 2,640 pounds), which would then be further enriched by Russia and converted into fuel by France before being supplied to a Tehran reactor.

"The amount they mentioned for the swap is not acceptable ... and our experts are still studying it," Mottaki said when he announced Iran's rejection of the deal.