"They are there now," International Atomic Energy Agency director general Rafael Grossi told reporters in Washington.

"Today they are inspecting Bushehr," Grossi said.

Iran's Atomic Energy Organization said earlier that IAEA inspectors would oversee the replacement of fuel at the Bushehr, a major nuclear power site in southwestern Iran that was spared in an Israeli military campaign in June.

Iran did not say whether the IAEA would be allowed access to other sites, including Fordo and Natanz, which were hit during the war.

Grossi said discussions about inspecting other sites were underway with no immediate agreement.

"We are continuing the conversation so that we can go to all places, including the facilities that have been impacted," Grossi said.

He said that Iran cannot restrict inspectors only to "non-attacked facilities."

"There is no such thing as a la carte inspection work," he said.

Grossi met senior US officials during his visit, which came as Iran held talks with European powers to avoid a "snapback" of sanctions.

Iran has warned of grave consequences for the move, although Grossi said that Iran has not told the IAEA explicitly that it would kick out inspectors.