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.

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 tripled its rate of production of near weapons-grade uranium in recent weeks, according to a new report.

The action could lead to sanctions against Tehran, which has barred international monitoring of its accelerated uranium enrichment efforts.