Israel said it had targeted the intelligence headquarters of Hezbollah in Beirut and was assessing the damage on Friday after a series of strikes on senior figures in the group that Iran's Supreme Leader dismissed as counterproductive.

Israel has been weighing options in its response to Iran's ballistic missile attack on Tuesday, which Iran had carried out in response to Israel's military action in Lebanon, Reuters reported.

Oil prices have risen on the possibility of an attack on Iran's oil facilities as Israel pursues its goals of pushing back Hezbollah militants in Lebanon and eliminating their Hamas allies in Gaza.

The air attack on Beirut, part of a wider assault that has driven more than 1.2 million Lebanese from their homes, was reported to have targeted the potential successor to the leader of Iran-backed Hezbollah, Sayyed Hassan Nasrallah, killed by Israel a week ago.

Hashem Safieddine's fate was unclear and neither Israel nor Hezbollah have offered any comment.

A blast was heard and smoke was seen over Beirut’s southern suburbs early on Saturday, Reuters witnesses said, as the Israeli military issued three alerts for residents of the area to immediately evacuate.

The first alert warned residents in a building in the Burj al-Barajneh neighbourhood and the second in a building in Choueifat district. The third alert mentioned buildings in Haret Hreik as well as Burj al-Barajneh.

In a statement early on Saturday, Hezbollah also said the Israeli army was trying to infiltrate the Lebanese southern town of Odaisseh and that clashes there were ongoing.

U.S. President Joe Biden said on Friday he would think about alternatives to striking Iranian oil fields if he were in Israel's shoes, adding that he thinks Israel has not yet concluded how to respond to Iran.

Biden was asked at a White House press briefing if he thought that by not engaging in diplomacy, Israeli Prime Minister Benjamin Netanyahu was trying to influence the Nov. 5 U.S. election in which Republican former President Donald Trump faces Democratic Vice President Kamala Harris.

"Whether he is trying to influence the election, I don't know but I am not counting on that," Biden said in response. "No administration has done more to help Israel than I have."

The government in Lebanon says more than 2,000 people have been killed there in the past year, most in the past two weeks.

U.N. spokesperson Stephane Dujarric called the toll on civilians “totally unacceptable.”

The Lebanese government has accused Israel of targeting civilians, pointing to dozens of women and children killed. It has not broken down the overall figure between civilians and Hezbollah fighters.

Israel says it targets military capabilities and takes steps to mitigate the risk of harm to civilians. It accuses Hezbollah and Hamas of hiding among civilians, which they deny.

The U.S. State Department said that an American was killed in Lebanon this week and Washington was working to understand the circumstances of the incident.

Kamel Ahmad Jawad, from Dearborn, Michigan, was killed in an Israeli airstrike on Tuesday, according to his daughter, a friend and the U.S. congresswoman representing his district.

State Department spokesperson Matthew Miller said the department was "alarmed" by the reports, and added: "it is a moral and strategic imperative that Israel take all feasible precautions to mitigate civilian harm."

The latest bloodletting in the decades-old Israeli-Palestinian conflict stems from an attack by Palestinian Hamas militants' Oct. 7, 2023, that killed 1,200 and in which about 250 were taken as hostages, according to Israeli tallies.

Israel's subsequent assault on Gaza has killed over 41,000 Palestinians, according to Gaza's health ministry, and displaced nearly Gaza's entire population, caused a hunger crisis and led to genocide allegations that Israel denies.

The Israeli military said some 70 projectiles were launched from Lebanon into Israeli territory on Friday evening and were either intercepted or fell in open land.

Israel sent ground forces into Lebanon this week after the Iranian missiles attacks. It has said its ground operations are "localized" in villages near the border, but has not specified how far into Lebanon they would advance or how long they would last.

Israel says the operations aim to allow tens of thousands of its citizens to return home after Hezbollah bombardments that forced them to evacuate from its north.

IRAN VOWS NOT TO BACK DOWN

Iran's missile salvo was partly in retaliation for Israel's killing of Hezbollah secretary-general Nasrallah, a dominant figure who had turned the group into a powerful armed and political force with reach across the Middle East.

Iranian leader Ayatollah Ali Khamenei told a huge crowd in Tehran that Iran and its regional allies would not back down.

Israel's adversaries in the region should "double your efforts and capabilities... and resist the aggressive enemy," Khamenei said in a rare appearance leading Friday prayers, at which he mentioned Nasrallah and called Iran's attack on Israel legal and legitimate.

He said Iran would not "procrastinate nor act hastily to carry out its duty" in confronting Israel.

The semi-official Iranian news agency SNN quoted Revolutionary Guards deputy commander Ali Fadavi as saying on Friday that if Israel attacked, Tehran would target Israeli energy and gas installations.

Axios reporter Barak Ravid cited three Israeli officials as saying that Hezbollah official Safieddine, rumoured to be Nasrallah's successor, had been targeted in an underground bunker in Beirut overnight but his fate was not clear.

Israeli Lieutenant Colonel Nadav Shoshani said on Friday the military was still assessing the Thursday night airstrikes, which he said targeted Hezbollah's intelligence headquarters.

Earlier the Israeli military reported that it had killed the head of Hezbollah's communication networks, Mohammad Rashid Sakafi. It declined to comment on the report that Safieddine was targeted.

Hezbollah made no comment on the fate of Sakafi.

Khamenei said assassinations would just spur more attacks.

"Every strike launched by any group against Israel is a service to the region and to all humanity," he said, adding that Afghanistan should join the "defence".

FLATTENED BEIRUT BUILDINGS

In Hezbollah's stronghold in Beirut's southern suburbs, many buildings have been reduced to rubble. Nearly all the storefronts in the main market street, Moawad Souk, were damaged and the road filled with broken glass.

"We're alive but don't know for how long," said Nouhad Chaib, a 40-year-old man already displaced from the south.

The Islamic Health Authority, a civil defence agency linked to Hezbollah, said 11 medics had been killed in three separate Israeli attacks across southern Lebanon on Friday.

The Israeli military said that in the past day it had struck several weapons storage facilities, command and control centres, and Hezbollah infrastructure sites in the Beirut area.

Iran's Foreign Minister Abbas Araqchi, visiting Beirut and meeting with top Lebanese officials, said Tehran supported efforts for a ceasefire in Lebanon provided it was backed by Hezbollah and was simultaneous with a Gaza ceasefire.