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 said Friday it had begun commissioning new advanced uranium-enrichment centrifuges after it was censured by the International Atomic Energy 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 has tripled its rate of production of near weapons-grade uranium in recent weeks, according to a new report.

The resolution renews longstanding demands for Iran to explain the presence of uranium traces at undeclared sites and provide the IAEA with expanded monitoring access. It emphasizes the need for Iran to comply with international safeguards and demonstrate that no undeclared nuclear materials are in use.