Drones and missiles crashed into oil facilities and US diplomatic missions in the Gulf as the Islamic republic retaliated, and Israel pushed troops deeper into Lebanon to battle the Tehran-backed militia Hezbollah after it entered the fray.

Israel announced a "large-scale wave" of strikes targeting Iran's capital Tuesday, with local media showing columns of smoke rising over the centre of town -- home to many government buildings -- and reporting an attack on one of the city's two airports.

"Their air defence, air force, navy, and leadership is gone. They want to talk. I said: 'Too late!'," Trump posted on social media, two days after he said he was open to talks and four days after US and Israeli strikes killed supreme leader Ayatollah Ali Khamenei.

Iran's ambassador to the UN in Geneva denied that his country had approached the US for talks.

According to Iranian media, US and Israeli strikes targeted a building on Tuesday in Qom belonging to the committee that is to elect a new supreme leader. The Tasnim news agency reported that strikes had already targeted the body's main headquarters in Tehran the day before.

During a meeting with Germany's chancellor in Washington, Trump said that "most of the people we had in mind" as possible successors to Khamenei were now dead after waves of strikes.

He also allowed that after committing to large-scale military action in Iran, "the worst case would be, we do this, and then somebody takes over who's as bad as the previous person".

Iran's foreign ministry spokesman said the UN Security Council "has a duty" to act to stop the war, even as its military remained publicly defiant in the face of the campaign.

A Revolutionary Guards general, Ebrahim Jabbari, said that if Iran's foes "hit our main centres, we will hit all economic centres in the region".

A drone attack caused a fire near the US consulate in Dubai on Tuesday, with US Secretary of State Marco Rubio saying it had hit a parking lot and that "all personnel are accounted for".

The US embassy in Riyadh was damaged and briefly caught fire overnight after an Iranian drone strike, and the US embassy in Kuwait City was struck by drones on Monday, diplomatic sources told AFP.

Economic targets came under fire elsewhere in the Gulf.

Qatar said it had downed missiles targeting Hamad International Airport in Doha, while Oman reported several drones attacking the port of Duqm, and in the UAE falling debris from an intercepted drone caused a fire at an oil storage and trading zone, authorities said.

On Tuesday evening, the Guards announced their latest salvo, saying "a large number of missiles" had been fired at Israel.

The Israeli military, meanwhile, announced a strike on an underground facility on the eastern outskirts of Tehran where it said Iranian "scientists operated covertly to develop a key component for nuclear weapons".

- Ghost town -

In Tehran, residents who have not fled remained shut away in their homes for fear of the US-Israeli bombardment.

The Iranian capital is normally home to around 10 million people, but in recent days "there are so few people that you'd think no one ever lived here", said Samireh, a 33-year-old nurse.

Authorities had previously urged people to leave the city, and police officers, armed security forces and armoured vehicles have been stationed at main junctions, carrying out random checks on vehicles.

In the more upmarket north of Tehran, the meowing of cats and birdsong replace the usual din of traffic jams.

Streets were largely deserted and most vehicles still on the road were supplying grocers and small local shops that were still open.

- Diplomatic, economic concerns -

Israel's Foreign Minister Gideon Saar urged foreign capitals on Tuesday to cut all ties with Tehran "following the Iranian regime's attacks on all its neighbours and the massacre of its own people".

China's Foreign Minister Wang Yi, according to the official Xinhua news agency, warned Saar in a call that Beijing opposes the strikes, saying the use of force "will only bring new problems".

The war has already sent shockwaves through world markets, with energy prices soaring and share prices falling.

Asian giant India added its concern to China's.

"Our trade and energy supply chains also traverse this geography. Any major disruption has serious consequences for the Indian economy," foreign ministry spokesman Randhir Jaiswal said.

After already halting LNG production, Qatar's state-run QatarEnergy said it would also stop some downstream production of substances including urea, polymers, methanol and aluminium.

- Lebanon front -

Israel said it was seizing new forward positions inside southern Lebanon, after Hezbollah fired missiles in support of its backer Iran, provoking a furious Israeli bombardment.

Defence Minister Israel Katz said Israeli forces had been authorised to "take control of additional strategic positions in Lebanon in order to prevent attacks on Israeli border communities".

Israel's army chief Eyal Zamir said it was set on eliminating the Hezbollah threat "and will not stop until this organisation is disarmed".

The military later said it had detected several projectiles launched towards Israel from Lebanon, most of which were intercepted.

Lebanese authorities said Tuesday that more than 58,000 people have been driven from their homes -- double the figure reported the previous day.

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