With thousands of advanced centrifuges on standby, Tehran says it is now spinning more, which could increase its stockpile of near-bomb-grade atomic fuel.

A rebuke of Iran led by the U.S. and its close allies at the global nuclear watchdog agency has drawn a vow by the Islamic republic to further ramp up uranium enrichment.

Iran announced Friday it was activating new advanced centrifuges – which enrich uranium for the country’s nuclear program – after the United Nations’ nuclear watchdog criticized the country for not cooperating with the agency.

Iran has defied international demands to rein in its nuclear program and has increased its stockpile of uranium enriched to near weapons-grade levels, according to a confidential report by the United Nations’ nuclear watchdog seen Tuesday by The Associated Press.

Iran said Friday it had begun commissioning new advanced uranium-enrichment centrifuges after it was censured by the International Atomic Energy Agency.

U.N. nuclear watchdog chief Rafael Grossi said on Wednesday he hopes Iran's move towards capping its stock of uranium just short of weapons grade will hold, as his agency's board was set to pass a Western-drafted resolution that could derail that.

Iran has increased its nearly weapons-grade uranium, a United Nations watchdog found, defying international demands to rein in its nuclear program.

Iran’s pledge to cease stockpiling uranium enriched close to the levels needed for nuclear weapons was made unconditionally and is the first time the nation has made such a proposal, according to the United Nations atomic watchdog.

Iran has raised the possibility it would stop expanding its stockpile of uranium enriched to a purity of 60 percent — very close to the level needed for a weapon, the U.N.’s nuclear watchdog says.