"I officially announce that Iran has joined the nuclear club," President Mahmoud Ahmadinejad was quoted by official media as telling a specially staged gathering in the eastern holy city of Mashhad.

Ranking Iranian officials, representatives of civilians and mullahs, and 15 ambassadors mostly from neighboring states attended the Mashhad gathering.

He elaborated that the Islamic Republic had obtained access to nuclear fuel cycle and produced low-grade enriched uranium which can be used to build nuclear power plant on Sunday. Enriched uranium is the key material for civil nuclear fuel cycle construction, but it can be used for building nuclear weapons at a degree of enrichment as high as 90 percent.

Accusing Iran of developing nuclear weapons covertly, the United States, along with the European Union, has been pressing the Islamic Republic to abandon the nuclear program, wielding UN sanctions.

"So far, Iran has completely mastered nuclear fuel cycle," Ahmadinejad declared.

The hardline president vowed simultaneously that Iran would forge ahead continuously on the path of nuclear development until the country reached the capability of industrial-scale uranium enrichment.

However, Ahmadinejad showed some degree of calmness by promising that future moves over the Iranian nuclear program would still be governed by the International Atomic Energy Agency (IAEA).

"Iran's nuclear activities have been under the complete supervision of the IAEA. The country will continue its activities under the agency's supervision and within the framework of the Non-Proliferation Treaty (NPT) in order to achieve industrial-scale uranium enrichment," the president said.

He stressed that Iran would be committed to its promise that the nuclear technology must be used for peaceful purpose due to its reliance on "the faith of its youth and the lofty values of the Iranian-Islamic culture."

The president warned the western countries not to "repeat their past mistake" by trying to prevent Iran from achieving its rights, a clear reference to the report and the hand-over of the Iranian nuclear file to the UN Security Council on Feb. 4 and March 8 respectively.

Soon after the nuclear case being reported to the UN, the Islamic Republic resumed small-scale uranium enrichment and barred snap inspections of the IAEA required by the additional protocol of the NPT.

At the gathering on Tuesday, Ahmadinejad's deputy and chief of Iran's Atomic Energy Organization Gholamreza Aqazadeh further detailed the president's announcement by saying that Iran has successfully "produced enriching uranium to the 3.5 percent".

Experts have pointed out that the technological gap between 3.5 percent and 90 percent is far less wide than that between a blank file and 3.5 percent enriched uranium.

Aqazadeh said that the achievement means that Iran has "passed the stage of pilot production" and has paved the way for launching 3,000 centrifuges by the end of the current Iranian calendar year(March 20, 2007).

The Iranian nuclear chief also revealed that Iran has produced 110 tons of uranium hexafluoride gas (UF6), the feedstock for enrichment, and the production of a heavy water reactor in Iran would be completed in two years.

Earlier in the day, the Kuwaiti News Agency quoted Iran's powerful former president and the incumbent Expediency Council Chairman Akbar Hashemi Rafsanjani as saying that Iran has launched 164 centrifuges at the uranium enrichment facility in the central town of Natanz and "got the industrial output".

"We prefer to develop the work in order to achieve a complete industrial unit," Rafsanjani said.

Hours after Iran's claim of nuclear membership, the United States soon warned that the Islamic Republic was "moving in the wrong direction".

"Iran's announcement had heightened concerns in the international community about the country's nuclear program," White House spokesman Scott McClellan told reporters.

Iranian officials' unanimous announcement of the sensitive technological achievement came just one day before a scheduled visit by IAEA Director General Mohamed ElBaladei and about two weeks before a deadline set by the UN Security Council for Iran to re-suspend all activities related to the enrichment.

The UN Security Council made the call in a non-binding presidential statement on March 29, granting Iran 30 days to comply, but the requirement has been rejected by Tehran as illegal. Thus, ElBaladei's visit had been viewed as a last-ditch effort to ease the escalating tension, but apparently, the UN nuclear chief is believed to be facing a tough nut.

Rafsanjani admitted on Tuesday that the situation of the Iranian nuclear issue had become "very complicated" and ElBaradei would encounter a new situation once he enters Iran.