The Iranian Foreign Minister says he has spoken by phone with the director of the U.N.’s nuclear watchdog agency after a report from the agency said Iran is further increasing its stockpile of uranium enriched to near weapons-grade levels.

Iran has increased its stockpile of uranium enriched to near weapons-grade levels, a confidential report by the UN nuclear watchdog said on Saturday. It called on Tehran to urgently change course and comply with the agency’s probe.

The preliminary U.S. proposal came as a confidential U.N. report described an Iranian initiative that had multiplied Tehran’s stockpile of near-bomb-grade uranium.