- Iran is on high alert after Israel said it would respond to an Iranian attack against it on Saturday night.
- Almost all were intercepted by Israeli air defences with support from the US, UK and other allies.
An Israeli missile has hit Iran, US officials have told the BBC's partner station CBS News.
Blasts were heard in the central province of Isfahan and flights have been suspended over several cities, Iranian media say.
Iran is on high alert after Israel said it would respond to an Iranian attack against it on Saturday night.
Iran fired more than 300 drones and missiles in its first-ever direct attack on Israel.
Almost all were intercepted by Israeli air defences with support from the US, UK and other allies.
The Iranian attack was in retaliation for an Israeli strike which killed senior Iranian commanders in Syria on 1 April.
Isfahan province is home to a large air base, a major missile production complex and several nuclear sites.
What we know so far
It's nearly two hours since we first heard reports of explosions in Iran. Here's what we know so far:
Two US officials have confirmed to the BBC's US partner CBS News that an Israeli missile has struck Iran
Early Friday morning, explosions were heard around the central city of Isfahan, Iranian media reported, saying three drones were destroyed after the country's air defence systems were activated
Isfahan is home to an Iranian air base and the province has several military sites. There are no reports so far that anything was hit and Iranian media says all nuclear facilities are safe
Meanwhile, several flights have been diverted around Iran's airspace, tracking sites show
Israel's military and the Pentagon have both declined to comment so far.
Some background
It comes after Iran launched more than 300 missiles and drones towards Israel on 13 April in an unprecedented attack. Tehran has maintained this attack was in response to a suspected Israeli strike on its Syria consulate which killed 13 people
Israel and Western allies were able to down most of them before they reached Israeli territory
Israel had indicated that it would hit back to deter Iran from striking again, though international leaders have been urging the country to show restraint.
Iran state TV correspondent says Isfahan city is 'safe'
Iran's state broadcaster IRIB is downplaying the reports of an attack.
It has posted a video on Telegram showing one of its reporters standing on the top of a building in the centre of the city of Isfahan.
"The city is safe and sound, people are living their normal lives," he says.
"A couple of hours ago sounds were heard in the skies. From what we know, multiple mini-drones were flying in the skies of Isfahan when they were targeted.
"So far, provincial authorities have not given us any information. Some outlets had said that Isfahan's nuclear facilities were targeted, but based on our research this information is false, no place has been targeted."
Isfahan 'centre' of Iranian nuclear programme - former US official
Former US Assistant Secretary of state Mark Kimmitt has been speaking to BBC News about the significance of Isfahan and why Israel might have chosen it as the site of a strike.
“Isfahan is to a great extent the centre of the Iranian nuclear programme in terms of training, research and, what some would say, the development of the Iranian nuclear capability.
“So it’s a likely site that Israel would hit because the greatest fear the Israelis have is not continued missiles today but a nuclear capability tomorrow.”
US officials have told CBS, the BBC's US partner, that an Israeli missile has struck Iran, but the scale of any strike, the exact target, and whether its target was hit remains unclear.
Shadow war out in the open
All week there’s been speculation about when and how Israel would retaliate for last weekend's unprecedented Iranian attack – which brought the shadow war between these two long-time enemies dangerously into the open.
Now, Iran’s Fars news agency says explosions have been heard near an army base in the city of Isfahan – activating local air defence systems.
Flights are reported to have been suspended over several Iranian cities.
On Saturday night, Iran launched more than 300 attack drones and missiles at Israel.
With the help of allies, most were downed before reaching Israeli territory. Israeli officials had indicated that they had to hit back at Iran’s strike to deter it from acting again.
Australia tells citizens to leave Israel
Australia is urging its citizens to leave Israel “if it’s safe to do so”, following reports of an Israeli strike on Iran.
“There’s a high threat of military reprisals & terrorist attacks against Israel & Israeli interests across the region. The security situation could deteriorate quickly,” the Department of Foreign Affairs and Trade said on its Smartraveller account on X.
“We urge Australians in Israel or the Occupied Palestinian Territories to depart,” it continued.
It also warned Australians in the region of airspace closures, flight cancellations and other travel disruptions.
Tehran's main airport resumes flights - Iran state media
Iran’s state news agency, IRNA, reports that flights have resumed at Tehran’s Imam Khomeini International Airport.
Flights were earlier suspended across much of Iran as explosions were reported in the central province of Isfahan.
No missile attack in Iran: official
There's been a direct denial of a missile attack on Iran from an Iranian space agency official on X.
Hossein Dalirian wrote: "There has been no air attack from outside borders to Isfahan or other parts of the country."
He said Israel had "only made a failed and humiliating attempt to fly quadcopters [drones] and the quadcopters have also been shot down."
Iranian state media have reported similarly, saying that air defence systems were activated in several areas of the country overnight to engage possible targets, but there were no reports of any direct impact or explosion.
It adds that all facilities, including nuclear facilities, are safe.
Iran general reports 'no damage' in Isfahan - state media
Iranian state media are citing an army general in Isfahan province as saying that no damage has been reported.
"The strong sound heard in Isfahan was due to air defence firing at suspicious objects. There's been no damage,” he says.
Iran news agency video shows Isfahan nuclear facility
Iran’s semi-official Tasnim news agency, which is close to the Islamic Revolution Guard Corps (IRGC), has posted a video with a caption saying: “Isfahan’s nuclear site is completely safe”.
The footage appears to show a man checking his watch near the Isfahan Nuclear Technology Centre. The camera then zooms in on several troops standing around what looks like an air defence battery.
According to the World Nuclear Association, the Isfahan Nuclear Technology Centre includes a uranium conversion facility (UCF), which produces uranium hexafluoride.
Iran feeds uranium hexafluoride gas into centrifuges to produce enriched uranium, which can be used to make reactor fuel but also nuclear weapons.
Next to the UCF is an enriched uranium oxide powder plant (EUPP), which converts uranium hexafluoride into uranium oxide, and a fuel fabrication plant that produces fuel for the Tehran Research Reactor.
Uranium oxide can be converted into uranium metal. Iran has said it plans to use uranium metal to produce reactor fuel, but it could also be used to make the core of a nuclear bomb.
The Isfahan Nuclear Technology Centre also operates four small nuclear research reactors supplied by China.
Iran insists its nuclear activities are entirely peaceful and denies it has any ambitions to develop nuclear weapons. But Israel accuses Iran of developing nuclear capability that could be used to make a weapon.
US media says Israel gave Washington advance warning
The US was told about Israel's plans to strike, but they did not endorse the action, unnamed officials are telling some American media outlets.
Both NBC and CNN have reported unnamed officials saying that Israel gave Washington advance warning.
"We didn't endorse the response," CNN quoted an official saying.
The White House and Pentagon are both yet to issue any comment on the reported strike, which Iran says amounted to only a few drones.
Iran has dismissed reports of a missile attack, with one official saying "The news of the American media is not true".
Iran says all flight restrictions have now been lifted
When news broke earlier of a possible Israeli strike against Iran, significant flight diversions started taking place across the country’s airspace, according to monitoring site FlightRadar24.
Flydubai also told several news outlets that it would be cancelling all flights to Iran on Friday and that a flight from Dubai to Tehran had been turned around.
Iran is now signalling that the disruption is over and that it’s business as usual at its airports.
State news agency IRNA reported that flights have resumed at Tehran’s Imam Khomeini International Airport.
Meanwhile, Iran’s civil aviation organisation said restrictions previously put in place across several other airports have been lifted, according to Tasnim, a semi-official news agency.
Earlier state-run Mehr TV said that airports in Tehran, Isfahan, Shiraz and across the country’s West, North West and South West, had all been impacted.
US restricts travel for embassy staff in Israel
The US has restricted travel for its embassy personnel in Israel and their family members "out of an abundance of caution" following reports of Israel's retaliatory strike on Iran.
The embassy said staff have been told not to travel outside the greater Tel Aviv region - including Herzliya, Netanya, and Even Yehuda - and the Jerusalem and Be’er Sheva areas until further notice.
"The security environment remains complex and can change quickly depending on the political situation and recent events," it said in a statement on Friday.
Downing Street says 'Israel has a right to self-defence'
Hours after the reports of attacks on Isfahan in Iran, there is a reaction from the UK.
Downing Street says its understanding is that the source of the strikes on Iran has not been officially confirmed.
But the prime minister’s office says Israel has a right to self-defence, and added “we have been stressing to Israelis that what matters now is de-escalation".
So far there is no official statement from Israel that is claiming responsibility for the attack, but the US officials who spoke to the US media say that Israel conducted the strikes.
'Iran has no plan for immediate retaliation' - Iranian official
A senior Iranian official tells Reuters news agency "Iran has no plan for immediate retaliation against Israel," hours after an attack on the Iranian city of Isfahan, that is reported to have been conducted by Israel.
Two US officials told media the attack came from Israel, but Israel has not claimed responsibility so far.
"The foreign source of the incident has not been confirmed. We have not received any external attack, and the discussion leans more towards infiltration than attack," the Iranian official said on condition of anonymity.
Only about an hour ago, an Iranian analyst told Iranian state TV that "Mini drones shot down by air defences in Isfahan were flown by infiltrators from inside Iran", downplaying the reports that Israel had conducted the attack.
Oman, a mediator in the Middle East, condemns the attack on Iran
Oman has condemned the reported Israeli attack on Iran.
In a statement from the foreign ministry, they condemned "the repeated Israeli military attacks in the region as well".
Oman has been acting as a mediator in the Middle East attempting to de-escalate the situation.
France also calls for de-escalation in the region, with Deputy Foreign Minister Jean-Noel Barrot saying "France's position is to call on all actors for de-escalation and restraint".