Prime Minister Benjamin Netanyahu said on Tuesday Israeli airstrikes had killed two successors to Hezbollah's slain leader, as Israel expanded its ground offensive against the Iran-backed group with a fourth army division deployed into south Lebanon, Reuters reported.

Netanyahu spoke in a video released by his office hours after the deputy leader of Hezbollah, which is reeling after a spate of killings of senior commanders in Israeli airstrikes, left the door open to a negotiated ceasefire.

"We've degraded Hezbollah's capabilities. We took out thousands of terrorists, including (Hassan) Nasrallah himself and Nasrallah's replacement, and the replacement of the replacement," Netanyahu said, without naming the latter two.

Israeli Defence Minister Yoav Gallant said Hashem Safieddine, the man expected to succeed Nasrallah, had probably been "eliminated". It was not immediately clear whom Netanyahu meant by the "replacement of the replacement".

Later, Israeli military spokesman Daniel Hagari said Israel knew Safieddine was in Hezbollah's intelligence headquarters when fighter jets bombed it last week and Safieddine's status was "being checked and when we know, we will inform the public."

Safieddine has not been heard from publicly since that airstrike, part of an escalating Israeli offensive after a year of border clashes with Hezbollah. The group is the most formidably armed of Iran's proxy forces across the Middle East and has been acting in support of Palestinian militants fighting Israel in Gaza.

"Today, Hezbollah is weaker than it has been for many, many years," Netanyahu said.

Israel's military said on Tuesday that heavy air strikes against underground Hezbollah installations in southern Lebanon over the prior 24 hours killed at least 50 fighters including six sector commanders and regional officials.

The heightened regional tensions kindled a year ago by Palestinian armed group Hamas' attack from Gaza on southern Israel have escalated in recent weeks to engulf Lebanon, read the report.

On Oct. 1, Iran, sponsor of both Hezbollah and Hamas, fired missiles at Israel. On Tuesday, Iran warned Israel not to follow through on threats of retaliation.

Its foreign minister said any attack on Iran's infrastructure would be avenged while a senior Iranian official told Gulf states it would be "unacceptable" and would draw a response if they allowed their airspace to be used against Iran.

Western powers are seeking a diplomatic solution, fearing the conflict could roil the wider, oil-producing Middle East.

The Pentagon on Tuesday announced that Gallant will not go ahead with a visit to Washington and a meeting with his U.S. counterpart, Lloyd Austin, planned for Wednesday.

In a televised speech from an undisclosed location, Hezbollah's deputy leader Naim Qassem said he backed attempts to secure a truce.

For the first time, the end of war in Gaza was not mentioned as a pre-condition to halting the combat in Lebanon. Qassem said Hezbollah backed moves by Speaker of Parliament Nabih Berri, a Hezbollah ally, to secure a halt to the fighting.

Netanyahu's office declined to comment on Qassem's remarks. U.S. State Department spokesperson Matthew Miller told a briefing in Washington that Hezbollah had "changed their tune and want a ceasefire" because the group is "on the back foot and is getting battered" on the battlefield.

Qassem said Hezbollah's capabilities were intact despite "painful blows" from Israel. "Dozens of cities are within range of the resistance's missiles. We assure you that our capabilities are fine."

The Israeli military said it had sent the 146th Division into south Lebanon, the first reserve division to have been deployed over the border, and was extending ground operations against Hezbollah from southeast Lebanon into its southwest, Reuters reported.

A military spokesperson declined to say how many troops were in Lebanon at one time. But the military had previously announced that three other army divisions were operating there, meaning that thousands of soldiers were likely on Lebanese soil.

The Israeli military announced on Oct. 1 that ground forces had entered Lebanon, initially with commando units that were then followed by regular armoured units and infantry units.

Overnight, Israel again bombed Beirut's southern suburbs where Hezbollah is headquartered and said it had killed a figure responsible for budgeting and logistics, Suhail Hussein Husseini - the latest in a string of assassinations of some of Hezbollah's top officials.

The Israeli military on Tuesday issued a new evacuation warning for residents, especially in specific buildings in Beirut's southern suburbs, where Hezbollah has its headquarters, read the report.

In northern Israel not far from the Lebanon border, warning sirens sounded regularly throughout Tuesday as authorities said Hezbollah fired almost 200 rockets into Israel.

An Israeli military spokesperson said over 3,000 rockets had been fired into Israel from Lebanon so far in October, but interceptions by air defences had prevented many casualties and significant damage.

Targets on Tuesday again included Haifa, the northern port city where there were multiple reports of damage to buildings from missile debris. Israel's military said it had struck the launchers that fired the missiles at Haifa.

The mushrooming Israeli-Hezbollah conflict has killed well over 1,000 people in Lebanon in the past two weeks and prompted the mass flight of more than a million.

Israel's stated objective is to make its northern areas safe from Hezbollah rocket fire and allow thousands of displaced residents to return.

Hamas leader-in-exile Khaled Meshaal said the Palestinian group would rise "like a phoenix" from the ashes despite heavy losses during a year of war with Israel, and that it continues to recruit fighters and manufacture weapons, Reuters reported.

One year after the Hamas attack that triggered the war, Meshaal framed the conflict with Israel as part of a broader narrative spanning 76 years, dating back to what Palestinians call the "Nakba" or "catastrophe," when many were displaced during the 1948 war that accompanied the creation of Israel.

"Palestinian history is made of cycles," Meshaal, 68, a senior Hamas figure under overall leader Yahya Sinwar, told Reuters in an interview.

"We go through phases where we lose martyrs (victims) and we lose part of our military capabilities, but then the Palestinian spirit rises again, like the phoenix, thanks to God."

Meshaal, who survived an Israeli assassination attempt in 1997 after he was injected with poison and was overall Hamas leader from 1996-2017, said the Islamist militant group was still able to mount ambushes against Israeli troops.

"We lost part of our ammunition and weapons, but Hamas is still recruiting young men and continues to manufacture a significant portion of its ammunition and weapons," said Meshaal, without providing details.

Meshaal remains influential in Hamas because he has played a crucial role in its leadership for almost three decades, and is widely seen now as its diplomatic face. He is one of six Hamas leaders indicted by the U.S. Justice Department on terrorism charges over the Oct. 7 attack on Israel that triggered the war, read the report.

His comments appear intended as a signal that the group will fight on whatever its losses, Middle East analysts said.

"Overall I would say (Hamas is) alive and kicking still and ... will probably come back at some point in Gaza," said Joost R. Hiltermann, Middle East and North Africa Program Director of the International Crisis Group.

He said Israel had not spelled out a plan for Gaza when the war ends, and this could allow Hamas to re-establish itself although perhaps not with such strength or in the same form.

Israeli Prime Minister Benjamin Netanyahu's office declined comment on Meshaal's remarks.

Israel began its offensive against Hamas after about 1,200 people were killed and around 250 taken hostage in the Hamas attack on Oct. 7 last year, according to Israeli tallies.

Much of Gaza has been laid to waste and about 42,000 Palestinians have been killed in the offensive, according to Palestinian health officials.

Israel says Hamas no longer exists as an organised military structure and has been reduced to guerrilla tactics. At least a third of the Palestinian fatalities in Gaza, around 17,000 people, are Hamas fighters, according to Israeli officials. About 350 Israeli soldiers have been killed in combat in Gaza.

Meshaal said he saw no prospects for peace while Netanyahu's government is in power. Israel blames Hamas, whose founding charter calls for Israel's destruction, for the failure to secure peace.

"As long as the (Israeli) occupation exists, the region remains a ticking time bomb," Meshaal said.

North Korean leader Kim Jong Un said his country will speed up steps toward becoming a military superpower with nuclear weapons and would not rule out using them if it came under enemy attack, state news agency KCNA said on Tuesday.

Kim mentioned South Korean President Yoon Suk Yeol by name for the second time in a week in denouncing Seoul for colluding with Washington to destabilize the region to gloss over the fact it does not even have proper strategic weapons, Reuters reported.

"Yoon Suk Yeol made some tasteless and vulgar comment about the end of the Republic in his speech, and it shows he is totally consumed by his blind faith in his master's strength," KCNA quoted Kim as saying, referring to the South's alliance with the U.S.

"To be honest, we have absolutely no intention of attacking South Korea," he said in the speech at the Kim Jong Un National Defense University, a training ground for elite military specialists. "Every time I stated our position on the use of military force, I clearly and consistently used the qualification 'if.'"

"If the enemies try to use force against our country, the Republic's military will use all offensive power without hesitation. This does not preclude the use of nuclear weapons."

"Our footsteps towards becoming a military superpower and a nuclear power will accelerate," he added.

North Korea has for decades pursued a nuclear weapons programme and is believed to have enough fissile materials to build dozens of the weapons. It has conducted six underground nuclear detonation tests, read the report.

Last week, South Korea marked an annual armed forces day with a large military parade showcasing a ballistic missile capable of carrying a massive warhead and featuring a flypast of a U.S. strategic bomber.

In his address that day, Yoon warned the North against using nuclear weapons. "That day will see the end of the North Korean regime."

KCNA said Kim made the remarks on Monday, the same day the North has said its Supreme People's Assembly would meet to discuss amending the country's constitution. The news agency has made no mention of the assembly's deliberations since Monday.

The session is being closely watched because of the likelihood it would approve a constitutional amendment to reflect Kim's statement that unification is no longer possible and the South was a separate country and "a principal enemy."

Such a move would formalise Kim's break with decades-old goal espoused by both countries of national unification and attempts to improve ties, including a 2018 summit where their leaders declared there will be no more war and a new era of peace has opened.

In a separate report, KCNA said Kim sent a birthday message to Russian President Vladimir Putin, calling him his "closest Comrade and saying "strategic and cooperative relations" between the two countries will be raised to a new level, Reuters reported.