Iran has foiled an attempted sabotage attack against a building belonging to the country’s atomic energy agency, according to state television.
No casualties or damage were reported following the incident on Wednesday morning, it said.
It provided no further details, but said an investigation was under way.
There have been a number of attacks on nuclear sites in Iran over the past year. Iranian authorities have accused Israel of being behind some of them.
They include two explosions at the Natanz uranium enrichment plant.
The first blast, in July 2020, destroyed a workshop manufacturing centrifuges needed to produce enriched uranium, which can be used to make reactor fuel but also nuclear bombs. The second, this April, reportedly tore apart an underground centrifuge hall.
Israel neither confirmed nor denied involvement in either incident, though the former head of the Mossad intelligence agency hinted earlier this month that it was behind the most recent one.
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Iran’s state-run Irna news agency said the attempted attack on the building belonging to the Atomic Energy Organization of Iran (AEOI) was thwarted because of the “tight security measures” in place.
“The issue is now under investigation to identify its perpetrators,” it added.
“Such acts of sabotage aiming to disrupt Iranian nuclear activities have not been able to disturb continuation of Iran’s nuclear programmes.”
It comes as Iran and world powers attempt to revive a 2015 nuclear deal.
The agreement has been close to collapse since 2018, when then-US President Donald Trump abandoned it and reinstated sanctions that have crippled the Iranian economy. Iran retaliated by gradually breaching agreed limits on its nuclear activities, including those on uranium enrichment.
US President Joe Biden wants to rejoin the deal, but he says Iran must return to compliance before the sanctions are lifted. Iran insists that Mr Biden must lift the sanctions first.
Envoys of Iran and the five world powers still party to the deal – China, France, Germany, Russia and the UK – have been attempting to agree a compromise at talks in Vienna, with US representatives participating indirectly.
After meeting his US counterpart on Wednesday, German Foreign Minister Heiko Maas said progress was being made but that there were “still some nuts to crack”, including several technical questions.
He also said there was a “good chance” of an agreement even after outgoing Iranian President Hassan Rouhani, a moderate, is succeeded in August by Ebrahim Raisi, a hardliner who is deeply opposed to the West.
Mr Raisi warned on Tuesday that he would not allow the talks to be “dragged out” and that any agreement needed to guarantee Iran’s national interests.