The latest missile barrage came hours after Israel said it had destroyed Iran's internal security headquarters in Tehran, and as it reported a new wave of attacks targeting missile systems and storage sites in the country's west.

Khamenei also warned the United States against becoming involved in the conflict, after US President Donald Trump appeared to flirt with the idea in recent days, calling for Tehran's "unconditional surrender".

"This nation will never surrender," Khamenei said in a televised address, in which he called Trump's ultimatum "unacceptable".

"America should know that any military intervention will undoubtedly result in irreparable damage."

Iran's state television reported the launch of Fattah hypersonic missiles, while the Islamic Revolutionary Guards Corps also announced the launch of so-called super-heavy, long-range missiles.

An Israeli military official, who asked not to be named, said Wednesday that Iran had fired around 400 ballistic missiles and 1,000 drones since Friday. 

About 20 missiles had struck civilian areas in Israel, the official added.

Israeli Defense Minister Israel Katz said earlier that air force jets had destroyed Iran's internal security headquarters, as AFP journalists in Tehran reported powerful explosions across the city.

Meanwhile, a London-based internet watchdog said there was a "near-total national internet blackout" in Iran on Wednesday after days of disruptions.

Iran later announced heavier internet restrictions to curb hostile use, according to the Fars news agency. It first imposed internet curbs at the outset of Israel's campaign last week.

'Unconditional surrender'

Trump has fueled speculation about US intervention, saying Wednesday that his patience had "run out" with Iran, but that it was still not too late for talks.

He later said he has not yet made a decision on whether to join Israel in bombing Iran and warned that the country's current leadership could fall as a result of the war.

A change in Iran's government "could happen," he told reporters at the White House.

A day earlier Trump had boasted that the United States could assassinate Khamenei, but would not do so, "at least not for now".

Israeli Prime Minister Benjamin Netanyahu thanked Trump for his "support in defending Israel's skies" on Wednesday, calling him a "great friend" of Israel.

Iran's Foreign Minister Abbas Araghchi insisted in a post on X that his country remains committed to diplomacy, even as it acts in "self-defense" against Israel.

"Iran has so far only retaliated against the Israeli regime and not those who are aiding and abetting it," he said.

Russian President Vladimir Putin said Thursday that a deal to end the fighting was possible, that would guarantee both Israel's security and Iran's desire for a civilian nuclear program.

"I believe it would be good for all of us together to look for ways to stop the fighting and seek ways for the participants in the conflict to find an agreement," he told foreign journalists, including AFP, at a televised event.

Putin also said Iran had not asked Russia for military help.

A missile is fired from Iran toward Israel on June 18, 2025, on the sixth day of fighting between the two foes. (AFP/Atta Kenare)

'Painful losses'

Netanyahu said in a televised statement Israel was "striking the ayatollahs' regime with tremendous power" but acknowledged Israel had also suffered "painful losses".

Since Friday, at least 24 people have been killed in Israel and hundreds wounded, according to Netanyahu's office.

Iran said Sunday that Israeli strikes had killed at least 224 people, including military commanders, nuclear scientists and civilians. It has not issued an updated toll since then.

Israel said its surprise air campaign was aimed at preventing Iran from acquiring nuclear weapons -- an ambition Tehran denies.

Israel has maintained ambiguity regarding its own atomic activities, but the Stockholm International Peace Research Institute (SIPRI) says it has 90 nuclear warheads.

Beyond the deadly strikes, some Iranians have reported shortages in recent days.

Finding fuel has become a challenge, with long car queues waiting hours in front of petrol stations, a 40-year-old Iranian driver told AFP at the Iraqi border crossing of Bashmakh.

"There are shortages of rice, bread, sugar and tea," he said, asking to remain anonymous for fear of reprisals.

"People are shocked and distraught, they don't know what they should do," said a car dealer in the Iranian city of Bukan who also asked not to be identified by his real name.

Centrifuges hit

Earlier, Israeli strikes destroyed two buildings making centrifuge components for Iran's nuclear program in Karaj, a satellite city of Tehran, the International Atomic Energy Agency said.

In another strike on a site in Tehran, "one building was hit where advanced centrifuge rotors were manufactured and tested", the agency added.

Centrifuges are vital for uranium enrichment, the sensitive process that can produce fuel for reactors or, in highly extended form, the core of a nuclear warhead.