Iran's missile strikes on Israel were "correct, logical, and lawful", Ayatollah Ali Khamenei told a vast crowd which had gathered to hear him speak in Tehran on Friday.

The country's supreme leader described the attack as the "minimum punishment" for what he called Israel's "astonishing crimes" while leading Friday prayers in the capital, something he has not done since 2020.

Khamenei's speech came three days after Iran fired nearly 200 missiles at Israel, in what it said was retaliation for the assassination of Hezbollah?s leader, Hassan Nasrallah.

The Farsi-speaking supreme leader delivered part of his speech in Arabic to address Palestinian and Lebanese supporters.

During his sermon, Khamenei praised Nasrallah and voiced support for Hamas and Hezbollah, which he said provided "vital service to the entire region and the entire Islamic world".

He said Iran-aligned armed groups "will not back down" in their conflict with Israel, which entered a new phase after Hamas launched deadly raids into Israel almost one year ago.

Iran is the main backer of Hezbollah and Hamas, as well as other armed groups around the Middle East which have attacked Israel. They often dub themselves the "Axis of Resistance".

In recent weeks, several senior leaders of Iran-backed groups and Iran's powerful military wing, the Revolutionary Guards, have been killed in Israeli strikes or presumed Israeli assassinations.

The supreme leader's appearance in front of a crowd of tens of thousands in Tehran is a sign of the gravity of the moment for the Iranian regime, which is facing widespread domestic discontent.

It could be read as an attempt to show strength and restore Iran?s credibility as leader of the ?Axis of Resistance?.

The public appearance was also intended to show that Khamenei is not in hiding, after reports emerged that he had been taken to a secure location following Nasrallah's assassination.

The Grand Mosalla Mosque was flooded with people after Iranians were given free transport to attend the sermon. A large Palestinian flag was seen in the crowd.

Khamenei holds ultimate power in Iran, but very rarely leads Friday prayers himself.

The last time he did was in 2020, after the US killed Iran's most senior military commander, Qassem Soleimani. The time before that was in 2012.

Iran is still reeling from the loss of its allies Nasrallah and Hamas's political leader Ismail Haniyeh, who was assassinated in Tehran in July.

Israel is widely considered to be behind Haniyeh's killing, though it has never commented on his death.

Khamenei also told the crowd that Iran would retaliate if, as expected, Israel launches a response to Tuesday's missile attack.

"If we needed to do that again, we would do it again in the future," Khamenei told supporters.

On Thursday, US President Joe Biden suggested a possible Israeli strike on Iran's oil infrastructure had been discussed, as Israel continued to weigh up how to strike back at Tehran. (BBC)

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