Israel has foreshadowed a possible ground invasion of Lebanon while widening its punishing airstrikes and deflecting a missile that Hezbollah said was aimed at Mossad’s headquarters.

Israel has hit more than 2000 “terrorist targets” since launching strikes in Lebanon, while a flurry of diplomacy is seeking to prevent all-out war.

On Thursday (AEST), Lieutenant General Herzi Halevi told troops positioned on Israel’s northern border with Lebanon that the airstrikes were to “prepare the ground” for what could be coming next.

“You hear the jets overhead; we have been striking all day,” he said, according to an Israel Defence Forces press release.

“This is both to prepare the ground for your possible entry and to continue degrading Hezbollah.”

Earlier, another top general also intimated that a ground operation could be imminent when Major General Ori Gordin said they “must be fully prepared for manoeuvres”.

As observers said the situation in the Middle East was turning pretty grim, US President Joe Biden warned an all-out war was possible.

But Biden said there was also the possibility of a settlement in Israel’s concurrent conflicts in the Gaza Strip and Lebanon.

“An all-out war is possible but I think there’s also the opportunity – we’re still in play to have a settlement that can fundamentally change the whole region,” Biden said in an appearance on US broadcaster ABC’s The View.

Missile aimed at Mossad

Israel widened its air strikes in Lebanon on Wednesday (local time) and shot down a missile Hezbollah said it fired at the Mossad spy agency near Tel Aviv.

Hezbollah claimed to have targeted the Mossad headquarters with what it described as a ballistic missile over central Israel.

It was the first time since the war broke out last October that one of its missiles had been sighted above Tel Aviv – Israel’s commercial hub and seen as a target with the potential to trigger an escalation in Israeli action.

Hezbollah said in a statement it had fired a ballistic missile targeting Mossad headquarters “in support of our steadfast Palestinian people in the Gaza Strip … and in defence of Lebanon and its people”.

Reuters could not independently confirm the type of rocket fired.

Israeli spokesman Nadav Shoshani said he could not confirm what Hezbollah’s target was when it fired the missile from a village in Lebanon.

“The result was a heavy missile, going towards Tel Aviv, towards civilian areas in Tel Aviv. The Mossad headquarters is not in that area,” he said.

Israeli officials said the missile fired at Tel Aviv was shot down with a David’s Sling missile, a surface-to-air missile designed to destroy tactical ballistic missiles at low altitude.

Hezbollah blamed Mossad for assassinations of its leaders.

It has also accused the spy agency of carrying out an operation last week in which booby-trapped pagers and radios of Hezbollah members exploded, killing 39 people and wounding nearly 3000.

Israel has neither confirmed nor denied involvement.

No let up

World leaders expressed concern that the conflict – running in parallel to Israel’s war in the Gaza Strip against Hamas – was rapidly intensifying as the death toll in Lebanon rose and thousands of people fled their homes.

US Secretary of State Antony Blinken said his country and its allies were working tirelessly to avoid a full-blown war between Israel and Hezbollah.

“Risk of escalation in the region is acute … The best answer is diplomacy, and our co-ordinated efforts are vital to preventing further escalation,” Blinken said at a meeting with Gulf Arab state officials and ministers in New York.

Israeli air strikes this week have targeted Hezbollah leaders and hit hundreds of sites deep inside Lebanon while the group has fired barrages of rockets into Israel.

The Israeli military said on Wednesday (local time) it was calling up two additional reserve brigades to the northern border to carry out operational activities.

“This will enable the continuation of combat against the Hezbollah terrorist organisation, the defence of the state of Israel, and create the conditions to enable the residents of northern Israel to return to their homes,” it said.

Hundreds of thousands of Lebanese have fled their homes and hospitals have filled with the wounded since an intensification of bombing on Monday, when more than 550 people were killed in Lebanon’s deadliest day since the end of a 1975-1990 civil war.

There was no let up on Wednesday.

Israel said its warplanes were carrying out extensive strikes in south Lebanon and the Bekaa Valley, a Hezbollah stronghold further north.

At least 51 people were killed and at least 223 wounded in Israeli strikes across Lebanon on Wednesday at five different locations, the Lebanese health minister said.

Israel has expanded the zones it has been striking since Tuesday night, with attacks for the first time on the beach resort town of Jiyyeh just south of Beirut and Maaysrah.

There were also strikes in Bint Jbeil, Tebnin and Ain Qana in the south, the village of Joun in the Chouf district near the southern city of Sidon, and Maaysrah in northern Keserwan district.

As many as half a million people may have been displaced in Lebanon, its foreign minister said.

In Beirut, thousands of displaced people who fled from southern Lebanon were sheltering in schools and other buildings.

More than 60 people were relocated by the Lebanese Army early on Wednesday from the Christian town of Alma Chaab, along the border with Israel, following strikes overnight.

-with AAP