Satellite imagery has shown Israel struck nuclear testing sites in its weekend air attacks on Iran, in addition to air defense systems, perhaps opening the way for future raids if threatened by Tehran.

Iran’s president, Masoud Pezashkian, wrote to the UN on Sunday warning that Tehran has the right to respond to the attacks while countries including the US, UK and France, said the cycle of tit-for-tat strikes must now end.

Images from satellite firm Planet Labs showed that in the four-hour attack overnight Saturday, a military base in Parchin near Tehran, where nuclear tests were allegedly conducted in the past, was damaged.

While Israel had been warned by its biggest ally, the US, not to strike Iran’s nuclear sites, Parchin was marked by Iran as military, not nuclear, allowing them to evade the veto. It was also one of the sites which had been banned from inspections by the UN’s nuclear team.

The UN atomic agency, IAEA, had marked it as a site where Iran once worked on nuclear weapons. At least three buildings were hit, including solid-propellant facilities for missiles.

David Albright, a former UN weapons inspector who heads the Institute for Science and International Security research group, and Decker Eveleth, an associate research analyst at CNA, a Washington think tank, told Reuters that as well as Parchin, Israel struck Khojir, which according to Eveleth, is a sprawling missile production site near Tehran.

In posts on X, Albright said commercial satellite imagery showed that Israel hit a building in Parchin called Taleghan 2 that was used for testing activities during the Amad Plan, Iran's defunct nuclear weapons development program shuttered in 2003.

Albright, head of the Institute for Science and International Security research group, was given access to the program's files for a book after they were stolen from Tehran by Israel's Mossad intelligence agency in 2018.

On X, he said the archives revealed that Iran kept important test equipment at the site called Taleghan 2. While Iran may have removed key materials before the airstrike, he said, "even if no equipment remained inside" the building would have provided "intrinsic value" for future nuclear weapons-related activities.

Analysis from the think tank, The Institute of Science, also said that while the UN’s International Atomic Energy Agency never visited the building, not deemed a high priority site, “it is possible Iran only removed the most incriminating equipment in its clean up effort, in the high explosive test chamber,” it said in a post on X.

The non-proliferation group research explained: “If so, Israel’s alleged destruction may have destroyed valuable equipment useful in further nuclear weapons development.”

From the imagery, Taleghan 2 appears to have been destroyed, as were the other three buildings associated with rocket motor production nearby and secured separately.

The photographs also confirm that Israel attacked another base, in Hujir east of Tehran, where buildings used to mix fuel for ballistic missiles were also damaged.

It is consistent with Israel’s policy of targeting nuclear related sites without touching the sensitive facilities such as the nuclear enrichment facility, Natanz.

Jason Brodsky, from United Against Nuclear Iran, said the attacks this weekend send “a very clear message” to Iran.

“Israel is laying the groundwork to attack your oil and petrochemical refineries in the next round should you retaliate,” he wrote on X after Israel struck with great accuracy air defences around Iran’s critical energy sites. While the facilities were avoided, there were clear warnings of what could come should Iran hit back.

The sites targeted by Israel, according to the New York Times, included defenses at the Bandar Imam Khomeini petrochemical complex, in Khuzestan Province; at the major economic port Bandar Imam Khomeini, adjacent to it; and at the Abadan oil refinery.

Air-defense systems were also struck in Ilam Province, at the refinery for the gas field, called Tange Bijar, officials told the newspaper, including one from Iran’s oil ministry.

Pezeshkian’s letter to the UN Secretary General said Iran “reserves its inherent right to legal and legitimate response to these criminal attacks at the appropriate time”.

World leaders have been urging for an end to the cycle of violence.

In the early hours of Sunday morning Tehran time, US Defense Secretary Lloyd Austin warned Iran against responding to Israel’s strikes.

After speaking to Israeli Defense Minister Yoav Gallant, he wrote on X: “ I reaffirmed the United States’ ironclad commitment to Israel’s security and support for Israel's right to defend itself … and made clear that Iran should not make the mistake of responding to Israel’s strikes, which should mark the end of this exchange.”

On Saturday, British PM Keir Starker said: "I am clear that Israel has the right to defend itself against Iranian aggression. I'm equally clear that we need to avoid further regional escalation and urge all sides to show restraint. Iran should not respond.”

The Israeli military said three waves of Israeli jets struck missile factories and other sites near Tehran and in western Iran early on Saturday in retaliation for Tehran's October 1 barrage of more than 200 ballistic missiles against Israel.

Playing down the damage, Iran’s military said the Israeli warplanes used "very light warheads" to strike border radar systems in the provinces of Ilam, Khuzestan and around Tehran.