on Monday announced that it had entered "industrial level" stage of nuclear fuel production, in defiance of a key UN sanction resolution demand of halting enrichment work.

At a ceremony here, Iranian President Mahmoud Ahmadinejad named Monday the country's first "National day of Nuclear Technology," underlining that world powers cannot stop Iran's nuclear drive from making progress.

"Enemies have used UN Security Council as a tool to block Iran's progress ... from today, Iran is among the producers of nuclear fuel at industrial level in the world," Ahmadinejad told hundreds of high-ranking officials and reporters at Iran's sensitive Natanz nuclear facilities.

"They (the West) should know that our nation with awareness and faith has stood by its leadership and will defend its rights to the end," said the president, adding "the great Iranian nation will never allow the bullying powers to put obstacles in its path of progress by influencing the international community."

The president's announcement suggested that Iran had been operating a large number of centrifuges at its nuclear sites, but he did not elaborate on how many centrifuges were already operational.

The UN Security Council passed Resolution 1747 in the end of last month, urging Iran to suspend uranium enrichment work "without further delay," or faces more severe sanctions.

Regarding the exact number of operational centrifuges in Natanz,there were some inconsistencies in Iranian officials' accounts.

When answering a question that if Iran had begun injecting gas into 3,000 centrifuges, National Security Council Secretary Ali Larijani said "Yes, we have injected gas." But he didn't explicitly say all the 3,000 machines had been installed.

But Mohammad Saeedi, the deputy head of Iran's atomic energy organization, told reporters the number of operating centrifuges in the Natanz nuclear facilities would be known in 20 days.

"I don't think there's any need now to declare the number of centrifuges to which (UF6) gas has been injected, you should wait for the next 20 days when IAEA (International Atomic Energy Agency)inspectors present their reports," said Saeedi.

Though the Iranian parliament has demanded the government to reduce its cooperation with IAEA, inspectors form the UN nuclear watchdog are still taking regular visits to Iranian nuclear plants.

Some observers have predicted that Ahmadinejad's announcement, came just five days after the end of a standoff over Iran's detention of 15 British sailors, would escalate the tension between Iran and the West.

Just one hour after Ahmadinejad's announcement, the U.S. State Department spokesman Sean McCormack responded by saying that the declaration illustrates that UN sanctions against Tehran were "justified."

"This is another signal that Iran is defying the international community," McCormack said.

The declaration also aroused mixed reaction in Iran.

"This is our nation's proud...and nobody can stop us from doing that," Nazanin Sariba, a female student of 28, told Xinhua.

Some expressed more cautious views. "This news wasn't something new but officially announcing it before hundreds of foreign delegations and ambassadors is something which can have both positive and negative results," Davoud Babak, a 35 years old clerk said in a telephone interview.

"Negative aspect may lead to further sanctions and positive aspect is for Iranians who don't need to worry about the energy in the future," he added.