Board members of the International Atomic Energy Agency are holding a meeting to discuss Iran's nuclear program, among other topics.
Iran's nuclear development is a major item on the agenda at the meeting that kicked off on Monday in Vienna.
The IAEA's latest report touches on the discovery of nuclear materials at undeclared sites in Iran, and its production of 60-percent enriched uranium, an action that breaches the 2015 nuclear deal with world powers.
The UN nuclear watchdog says Iran has failed to provide necessary explanations regarding these discoveries.
Speaking at the start of the meeting, IAEA Director General Rafael Grossi expressed grave concern about Iran not answering these questions.
Debate at the board meeting will likely affect how the indirect talks between the US and Iran will proceed. The negotiations aimed at reviving the nuclear agreement are expected to resume in Vienna this week.