Iran's top nuclear official was blocked from attending the International Atomic Energy Agency's General Conference in Vienna on Monday after pressure from the Trump administration, Bloomberg reported on Sunday, citing a US official who spoke on condition of anonymity.
Mohammad Eslami, Iran's vice president for nuclear affairs and head of the Atomic Energy Organization of Iran, had been scheduled to address the UN nuclear watchdog's gathering before Austria denied him entry, according to the official.
Iran's Mehr News Agency reported on Saturday that Eslami had left Tehran to attend the conference.
An Austrian government spokeswoman referred questions on the matter to the Foreign Ministry, which did not respond to Bloomberg's request for comment.
Austria's decision followed US pressure to deny Eslami a sanctions waiver requested by the UN that would have allowed him to enter the country, the US official said.
A lower-level Iranian representative may still address the conference later in the week, but Eslami's exclusion prevents one of Tehran's most senior nuclear officials from speaking at the opening of the annual gathering.
IAEA admits it has been 'blind' to Iranian nuclear program for over a year
The dispute comes just days after IAEA Director-General Rafael Grossi said the agency was "completely blind" regarding Iran’s nuclear program and has been since at least June 2025. He also reported that satellite imagery had picked up construction activity at Pickaxe Mountain
US President Donald Trump also repeatedly warned Iran against rebuilding sensitive nuclear infrastructure. Last week, he pointed to activity at Pickaxe Mountain and warned Tehran against attempts to rebuild there.
US Energy Secretary Chris Wright is expected to use the Vienna conference to deliver a direct warning to Tehran, according to excerpts of his prepared remarks provided to Bloomberg by a Trump administration official.
"Iran must fully cooperate with the IAEA, meet its safeguards obligations, and provide the access necessary for the agency to do its job," Wright is expected to say, per the excerpts.
Washington's pressure follows an IAEA Board of Governors resolution that reported Iran to the UN Security Council for breaches of its non-proliferation obligations.
Wright to emphasize IAEA's core mission of safeguards, peaceful nuclear technology
Wright is also expected to emphasize what he describes as the IAEA's core mission of nuclear safeguards, security, and promoting peaceful nuclear technology.
"We ask the agency to prioritize operational efficiency, eliminate redundant programs, and ensure that all funding contributed by member states is used to uphold the foundational promise that underpins the nuclear nonproliferation regime," according to the statement seen by Bloomberg.
"A disciplined IAEA, remaining focused on its core technical mandate, will prove beneficial to all member states."
Wright is expected to portray Washington as committed to both expanding nuclear power and maintaining strict non-proliferation standards.
"As America leads a new era of nuclear energy at home and around the world, we will prove that rapid growth and uncompromising standards go hand in hand," Wright is expected to say.
"American nuclear leadership means American technology backed by the world's highest standards of safety, security, and nonproliferation, protecting our national interests while strengthening the competitiveness of our companies and earning the trust of our partners."