Israel has attacked Iran’s capital, with explosions booming across Tehran as Prime Minister Benjamin Netanyahu says it targeted nuclear and military sites.

The head of Iran’s Revolutionary Guard, Hossein Salami, was killed in the strike on Friday morning, the country’s state media is reporting.

Iran state TV also announced high-level nuclear scientists Fereydoun Abbasi and Mohammad Mehdi Tehranchi were killed.

In addition, The Jerusalem Post reports it is increasingly likely that members of the Iranian army General Staff – including Chief of Staff Mohammad Bagheri – are among the casualties of the opening strikes.

The attack came as tensions reached new heights over Tehran’s rapidly advancing nuclear program.

In an address to the country, Netanyahu said Israel was at a “decisive point” in its history and was forced to act to stop Iran from producing a nuclear weapon “in a very short time”.

Netanyahu said the targets were: “Iran’s nuclear infrastructure, Iran’s ballistic missile factories, and Iran’s military capabilities.”

He said Israel was prepared for Iran’s “significant capabilities to harm us,” saying “we’re prepared for that.”

The strikes came after the Board of Governors at the International Atomic Energy Agency censured Iran for the first time in 20 years on Thursday, for it refusing to work with its inspectors.

Iran immediately announced it would establish a third enrichment site in the country and swap out some centrifuges for more-advanced ones.

“In recent months Iran has taken steps it has never taken before, steps to weaponised this enriched uranium,” Netanyahu said.

“If not stopped, Iran could produce a nuclear weapon in a very short time, could be a year, could be within a few months, less than a year. This is a clear and present danger to Israel’s very survival.”

Foreign minister Penny Wong said Australia is “alarmed by the escalation in tensions between Israel and Iran”.

“This risks further destabilising a region that is already volatile. We call on all parties to refrain from actions and rhetoric that would further exacerbate tensions,” Wong said.

“We all understand the need, the threat of Iran’s nuclear and ballistic missile program, it represents a threat to international peace and security and we urge the parties to prioritise dialogue and diplomacy,” she added.

Israel for years has warned it will not allow Iran to build a nuclear weapon, something Tehran insists it does not want – though officials there have repeatedly warned it could build them.

The US has been preparing for something to happen, withdrawing diplomats from Iraq’s capital and offering voluntary evacuations for the families of US troops in the wider Middle East.

On Friday, US Secretary of State Marco Rubio distanced the US from Israel’s action.

“Tonight, Israel took unilateral action against Iran. We are not involved in strikes against Iran and our top priority is protecting American forces in the region. Israel advised us that they believe this action was necessary for its self-defence,” he posted on X.

“President Trump and the Administration have taken all necessary steps to protect our forces and remain in close contact with our regional partners. Let me be clear: Iran should not target U.S. interests or personnel.”

The White House is yet to make any comment.

People in Tehran awoke to the sound of the blast. State television acknowledged the blast.

It was not immediately clear what was hit, though smoke could be rising from Chitgar, a neighbourhood in western Tehran.

There are no known nuclear sites in that area – but it was not immediately clear if anything was happening in the rest of the country.

An Israeli military official said that his country targeted Iranian nuclear sites, without identifying them.

Benchmark Brent crude spiked on the attack, rising nearly 5 per cent on the news.

Israeli Defence Minister Israel Katz said his country carried out the attack, without saying what it targeted.

“In the wake of the state of Israel’s preventive attack against Iran, missile and drone attacks against Israel and its civilian population are expected immediately,” he said.

The statement added that Katz “signed a special order declaring an emergency situation in the home front”.

“It is essential to listen to instructions from the home front command and authorities to stay in protected areas,” it said

As the explosions in Tehran started, President Donald Trump was on the lawn of the White House mingling with members of Congress.

It was unclear if he had been informed but he continued shaking hands and posing for pictures for several minutes.

Trump earlier said he had urged Netanyahu to delay taking action while the US continued negotiations with Iran.

“As long as I think there is a [chance for an] agreement, I don’t want them going in because I think it would blow it,” Trump said.

-with AAP