Israeli Defence Minister Israel Katz warned that "Tehran will burn" if Iran fires more missiles at Israel.

In a televised address Friday night, Iran's supreme leader Ayatollah Ali Khamenei vowed to bring Israel "to ruin".

International calls for restraint are multiplying, as fears grow the Middle East could be on the threshold of a broader conflict.

Here is what we know:

- Targeting air defences -

On Saturday, Israel's military said it was striking dozens of missile launchers in Iran after announcing it had targeted air defences with a wave of strikes in the Tehran area.

The air campaign, which has targeted surface-to-surface and surface-to-air missile infrastructure in Iran, has now given Israel "aerial freedom of action from west Iran all the way to Tehran", military spokesman Brigadier General Effie Defrin told journalists.

"Tehran is no longer immune," he said, adding that Israel had launched a "massive strike" involving more than 70 fighter jets overnight on targets in the Iranian capital.

- Iran's response -

Israel said dozens of missiles -- some intercepted -- had been fired in the latest salvos from Iran.

AFP images of the city of Ramat Gan near Tel Aviv showed blown-out buildings, destroyed vehicles and streets strewn with debris.

Iran's Revolutionary Guards said they had attacked dozens of targets in Israel.

The Israeli military said three people were killed and 76 wounded since Iran began its attacks.

- Nuclear talks -

The fiercest ever exchange of fire between the arch foes came amid ongoing talks between Tehran and Washington seeking to reach a deal on Iran's nuclear programme.

Before the Israeli strikes, they were set to hold a sixth round of negotiations in Oman on Sunday.

But Iran said it would be "meaningless" to attend the talks while it was under attack by Israel.

Tehran has consistently denied seeking to develop a nuclear weapon, but had been enriching uranium to 60 percent -- far above the 3.67-percent limit set by a largely obsolete 2015 agreement with major powers.

However, that is still short of the 90-percent enrichment threshold needed for a nuclear warhead.

- More Iranian generals killed -

The Israeli military said on Saturday its air strikes had killed more than 20 Iranian army and Revolutionary Guard commanders.

Iranian state media reported on Saturday that General Gholamreza Mehrabi, deputy head of intelligence of the armed forces general staff, and General Mehdi Rabbani, deputy head of operations, "were martyred".

On Friday, top brass killed included the head of the Revolutionary Guards, Hossein Salami, and armed forces chief of staff Mohammad Bagheri, with replacements swiftly named by Khamenei.

The Revolutionary Guards said its aerospace commander Amirali Hajizadeh was also killed. He was in charge of Iran's ballistic missile arsenal.

Iranian media said on Saturday that three more nuclear scientists were killed, bringing the total to nine -- a toll that Israel also reported.

Iran's ambassador to the United Nations said 78 people had been killed and 320 wounded in the first wave of Israeli strikes.

- Nuclear sites hit -

Israel's attacks started in the early hours of Friday, a day of rest and prayer in Iran, and continued through the day, at various sites.

A key target was a vast underground uranium enrichment facility in Natanz, which Israel hit several times, according to Iranian state television.

Israel said another strike later Friday on Iran's uranium conversion plant in Isfahan damaged infrastructure for reconverting enriched uranium.

But Iran said the damage was limited, both in Isfahan and at another uranium enrichment facility at Fordo.

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