Iran has fired air defence batteries as explosions were heard near one of its major air bases, raising fears of a possible Israeli strike following Tehran’s unprecedented drone-and-missile assault.

Iran’s Fars news agency said an explosion was heard at an airport in the central city of Isfahan, although the cause was not immediately known.

“The defence is activated in response to an object that is likely to be a drone,” sources have told Fars.

CNN reported that several flights had been diverted over Iranian airspace. State media confirmed flights were suspended over the cities of Isfahan, Shiraz and Tehran from early on Friday.

Isfahan is about four hours drive, or 350 kilometres, south of Iran’s capital, Tehran. It is home to a major military air base and there are several nuclear sites, including Natanz, centrepiece of Iran’s uranium enrichment program, in the region.

Despite the explosions, however, Israel is yet to take responsibility for any attack while Iranian officials have reportedly told Reuters there was no missile strike.

One Iranian government official suggested sites may have been targeted by drones.

State news agency IRNA said air defences had been fired across several provinces. It did not elaborate on what caused the batteries to fire, though people across the area reported hearing the sounds.

Tehran’s Imam Khomeini International Airport was closed to all flights until 7am GMT (5pm AEST), according to a notice to airmen posted on a US Federal Aviation Administration database.

Some flights over Iran early on Friday made sudden sharp turns away from the airspace, according to flight paths shown on tracking website Flightradar24.

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The Department of Foreign Affairs and Trade has issued a travel alert, warning Australians in the region to “depart if it’s safe to do so”.

“There’s a high threat of military reprisals and terrorist attacks against Israel and Israeli interests across the region. The security situation could deteriorate quickly. We urge Australians in Israel or the Occupied Palestinian Territories to depart if it’s safe to do so,” DFAT wrote on Smart Traveller’s X account on Friday afternoon.

Israel had said it would retaliate against Iran’s weekend attack, which involved hundreds of drones and missiles in retaliation for a suspected Israeli strike on its embassy compound in Syria.

Most of the Iranian drones and missiles were downed before reaching Israeli territory.

Analysts and observers have raised concerns about the risks of the Israel-Gaza war spreading into the rest of the region.

Iran told the UN Security Council on Thursday that Israel “must be compelled to stop any further military adventurism against our interests” as the UN secretary-general warned the Middle East was in a “moment of maximum peril”.

Oil prices jumped on the reports of the Israeli strike. Brent crude futures rose two per cent to $88.86 a barrel, the US dollar gained broadly, gold rose one per cent and S&P 500 futures dropped one per cent.

Israel’s assault on Gaza began after Palestinian Islamist group Hamas attacked Israel on October 7, killing 1,200, according to Israeli tallies. Israel’s military offensive has killed over 33,000 Palestinians in Gaza, according to the local health ministry.

Iran-backed groups have declared support for Palestinians, launching attacks from Lebanon, Yemen and Iraq.

-with AAP