Speaking to i24 News and The Jerusalem Post, Grossi stated that Iranian officials had cautioned him about the potential consequences of a raid.

“A strike could potentially have an amalgamating effect, solidifying Iran’s determination – I will say it plainly – to pursue a nuclear weapon or withdraw from the Treaty on the Non-Proliferation of Nuclear Weapons,” he said in an interview that was published on Monday.

Grossi added that he did not believe Israel would launch such an operation.

“But one thing is certain,” he continued, “The [Iranian] programme runs wide and deep. And when I say ‘deep’, I mean it. Many of these facilities are extremely well-protected. Disrupting them would require overwhelming and devastating force.”

Iranian officials have reiterated that Tehran has no intention of acquiring nuclear weapons, emphasizing that the country’s position is grounded in religious principles and the explicit fatwa of the Leader of the Islamic Revolution, Ayatollah Seyed Ali Khamenei.

He made his comments as Iran prepares a counteroffer to a US proposal for a new nuclear deal.

Iranian Ministry of Foreign Affairs spokesman Esmaeil Baghaei said on Monday that the US offer lacked key elements and failed to address sanctions relief – a longstanding demand from Tehran.

“We will soon submit our own proposed plan to the other side through Oman once it is finalised,” Baghaei added without elaborating on the details.

He also criticised the IAEA’s latest report on Iran’s nuclear programme as “unbalanced”, accusing it of relying on “forged documents” from Israel. The IAEA had recently described Iran’s cooperation as “less than satisfactory”, particularly in clarifying past nuclear activities at undeclared locations.

The US and Iran are trying to strike a new nuclear agreement after a 2015 agreement was abandoned by US President Donald Trump in 2018 during his first term.

Trump described Iran on Monday as a “tough” and skilled negotiator, as Washington continues indirect nuclear talks with Tehran.

“We’re doing a lot of work on Iran right now,” Trump stated during a White House economic event. “It’s tough … They’re great negotiators.”

The International Atomic Energy Agency said in a confidential report on Iran to member states on May 31 seen by Reuters that it had “conclusive evidence of highly confidential documents belonging to the Agency having been actively collected and analysed by Iran”.

The report added that “raises serious concerns regarding Iran’s spirit of collaboration” and could undermine the IAEA’s work in Iran, but Tehran announced in a statement to member states last week that the accusation in the report was “slanderous” and had been made “without presenting any substantiated proof or document”.

The IAEA’s 35-nation Board of Governors is holding a quarterly meeting this week. The United States, Britain, France and Germany plan to propose a resolution for the board to adopt that would declare Iran in breach of its non-proliferation obligations over other failings outlined in the report.

“Here, unfortunately, and this dates to a few years ago … we could determine with all clarity that documents that belong to the agency were in the hands of Iranian authorities, which is bad,” Grossi told a press conference.

“We believe that an action like this is not compatible with the spirit of cooperation.”

Asked about the nature of the documents and whether they were originally Iranian ones that had been seized by Israel and supplied to the agency, Grossi added: “No. We received documents from member states, and also we have our own assessments on documents, on equipment, etc.”