DUBAI – The Iranian Foreign Minister spoke by phone with the director of the U.N.’s nuclear watchdog agency early Sunday morning after a report from the agency said Iran is further increasing its stockpile of uranium enriched to near weapons-grade levels.

Writing on Telegram, Abbas Araghchi said he stressed Iran’s “continuous cooperation” in his conversation with Rafael Mariano Grossi, the head of the Vienna-based International Atomic Energy Agency. The IAEA did not immediately return a request for comment about the phone call.

The confidential IAEA report, which was seen by the Associated Press on Saturday, raised a stern warning, saying that Iran is now “the only non-nuclear-weapon state to produce such material” — something the agency said was of “serious concern.”

Araghchi emphasized to Grossi that all of Iran’s nuclear activities are within the framework of agreements and being monitored by the IAEA. The IAEA said in a separate report that Iran’s cooperation with the agency has been “less than satisfactory” when it comes to uranium traces discovered by IAEA inspectors at several locations in Iran that Tehran has failed to declare as nuclear sites.

Araghchi also asked Grossi to ensure “that certain parties do not exploit the agency for political agendas against the Iranian people.” European nations could take further steps against Iran based on the comprehensive report, leading to a potential escalation in tensions between Iran and the West.

Iran’s deputy foreign minister on Sunday published a detailed response, rejecting many of the report’s findings. Kazem Gharibabadi noted that out of the IAEA’s 682 inspections of 32 states, 493 were carried out in Iran alone.

“So long as a country’s nuclear activities are under the IAEA’s monitoring, there is no cause for concern,” he said. “The Islamic Republic of Iran is neither pursuing nuclear weapons nor does it possess any undeclared nuclear materials or activities.”

The IAEA report said that as of May 17, Iran has amassed 408.6 kilograms (900.8 pounds) of uranium enriched up to 60%.

That’s an increase of almost 50% since the IAEA’s last report in February. The 60% enriched material is a short, technical step away from weapons-grade levels of 90%.

The phone conversation between Araghchi and Grossi came hours after Omani Foreign Minister Badr al-Busaidi, who is mediating the U.S.-Iran talks, visited Tehran on Saturday to present the latest U.S. proposal for ongoing talks.

The U.S.-Iran talks are attempting to limit Iran’s nuclear program in exchange for the lifting of some of the crushing economic sanctions the U.S. has imposed on the Islamic Republic, which have strained relations for almost 50 years. The fifth round of talks between the U.S. and Iran concluded in Rome last week with “some but not conclusive progress,” al-Busaidi said at the time.