Iran’s supreme leader Ayatollah Ali Khamenei is not in Tehran, and has been transferred to a secure location, an official told Reuters on Saturday.

Talks between the US and Iran on Tehran’s nuclear programme ended inconclusively on Friday, with a suggestion that further discussions would be held next week. Trump had said he was “not happy” with the progress of discussions.

“The hour of your freedom is at hand,” Trump told Iranian citizens, urging them to “take over your government” once the operation is over.

Explosions were heard in Tehran, the Iranian capital, where smoke could be seen rising on the skyline, and several other cities. Iran has closed its airspace.

Sirens were sounded in Israel as the IDF said Iran had fired a “barrage of missiles” in retaliation.

A short time beforehand, Israel said it had launched “preventative” strikes on Iran.

Israeli prime minister Benjamin Netanyahu said the attacks aimed to “remove the existential threat” posed by the Iranian regime, as he urged the people of Iran to topple the government.

The operation is “massive and ongoing”, the US president said in a video on social media, pledging to use “overwhelming strength and devastating force” to destroy Iranian missiles and ensure it cannot develop a nuclear weapon.

The US has launched “major combat operations” in Iran, designed to eliminate “imminent threats” from the country’s regime, Donald Trump announced on Saturday.