TEHRAN, Iran - Iran has begun installing 3,000 centrifuges, a top lawmaker said yesterday in an announcement underlining that the country will continue to develop its nuclear program despite U.N. sanctions.

The lawmaker, Alaeddin Boroujerdi, said the installation under way at an Iranian uranium-enrichment plant "stabilizes Iran's capability in the field of nuclear technology," the news agency IRNA reported.

Three inspectors from the International Atomic Energy Agency (IAEA) who arrived in Iran yesterday were scheduled to visit the uranium-enrichment plant in Natanz, Iranian state-television reported.

Iran last week barred 38 inspectors from the U.N. nuclear watchdog because they came from countries that voted for sanctions on Iran. State television did not give the nationalities of the three inspectors, and the IAEA could not immediately confirm their arrival.

Iran's announcement appears to be its latest gesture of defiance toward the international community over its nuclear program. It faces the prospect of additional U.N. sanctions unless it stops uranium enrichment by the end of February.

The U.N. Security Council voted unanimously in favor of economic sanctions Dec. 23 after Iran ignored an earlier deadline to halt enrichment.

Large-scale use of centrifuges makes it possible to produce more enriched uranium in a shorter period.

Enriched uranium is used to fuel nuclear reactors and - at much higher levels of enrichment - to make nuclear weapons. Many countries, including the United States, believe that Iran is using its nuclear program as a cover to produce an atomic weapon. Iran says its program is only for generating electricity.

Iranian officials had said in recent weeks that the country was moving toward large-scale enrichment involving 3,000 centrifuges, which spin uranium gas into enriched material.

The comments from Boroujerdi, the head of the Iranian parliament's Foreign Policy and National Security Committee, came a day after IAEA head Mohamed ElBaradei said he believed Iran planned to begin work in February on an underground uranium-enrichment facility. The subterranean facility is intended to protect the nuclear project from attack.

There had been speculation the leadership might launch the project at Natanz next month to celebrate the 28th anniversary of the Islamic Revolution that brought the clerical leadership to power.

A senior State Department official warned Iran against accelerating its atomic program.

"If Iran takes this step, it is going to confront universal international opposition," Undersecretary of State Nicholas Burns said Friday. "If they think they can get away with 3,000 centrifuges without another Security Council resolution and additional international pressure, then they are very badly mistaken."

Iran ultimately plans to expand its program to 54,000 centrifuges.

In enrichment plants, centrifuges are linked in what are called cascades. For now, the only known assembled centrifuge cascades in Iran are above ground at Natanz, consisting of two linked chains of 164 machines each and two smaller setups.