After some of the heaviest cross-border exchanges of fire since the hostilities flared last October, Israel warned people in Lebanon to evacuate areas where it said the armed movement was storing weapons.
Tens of thousands are fleeing southern Lebanon due to Israeli atrocities , the Lebanese minister coordinating the crisis response, Nasser Yassin, told Reuters.
He said 89 temporary shelters in schools and the like had been activated, with capacity for more than 26,000 people so far.
Israeli Prime Minister Benjamin Netanyahu sent a short video statement addressed to the Lebanese people.
"Israel’s war is not with you, it’s with Hezbollah. For too long Hezbollah has been using you as human shields," he said.
After almost a year of war against Hamas in Gaza on its southern border, Israel is shifting its focus to the northern frontier, where Hezbollah has been firing rockets into Israel in support of Hamas, also backed by Iran.
Israel’s military said it had struck Hezbollah in Lebanon s south, east and north.
Lebanon’s health minister said 274 people had been killed, including 21 children and 39 women, and 1,024 wounded. One Lebanese official said it was Lebanon’s highest daily death toll from violence since the 1975-1990 civil war.
Netanyahu said Israel faced "complicated days" as it stepped up attacks in southern Lebanon, and urged Israelis to stay united.
"I promised that we would change the security balance, the balance of power in the north - that is exactly what we are doing," he said.
MORE AIRSTRIKES EXPECTED
On Monday evening an Israeli strike on Beirut s southern suburbs targeted senior Hezbollah leader Ali Karaki, the head of the southern front, but his fate was unclear, a security source told Reuters.
Earlier, Israeli Defence Minister Yoav Gallant said the campaign would continue until "we achieve our goal to return the northern residents safely to their homes". Hezbollah for its part has vowed to fight on until there is a ceasefire in Gaza.
The Israeli military said it had struck about 800 targets connected to Hezbollah in southern Lebanon and the Bekaa valley. "Among the targets struck were buildings where Hezbollah hid rockets, missiles, launchers, UAVs and additional terrorist infrastructure," it said in a statement.
Hezbollah has not commented on Monday s Israeli claims that it hid weapons in houses, which Reuters could not independently verify but it has said it does not place military infrastructure near civilians.
In response to the strikes, Hezbollah said it had launched dozens of missiles at a military base in northern Israel.
Sirens warning of Hezbollah rocket fire sounded across northern Israel, including in the port city of Haifa, and in the northern part of the occupied West Bank, the military said.
More attacks were expected in Lebanon.
Israel’s military spokesperson said Israeli aircraft were preparing to attack strategic Hezbollah weapons stashed in houses in the Bekaa valley and urged civilians to evacuate immediately.
"The sights now from south Lebanon are of secondary explosions of Hezbollah weapons, which are exploding inside houses," Rear Admiral Daniel Hagari said in a televised statement.
"In every house we are attacking there are weapons. Rockets, missiles, unmanned aerial vehicles that were meant for and aimed at killing Israeli civilians."
STRIKES PUT MORE PRESSURE ON HEZBOLLAH
The strikes have redoubled the pressure on Hezbollah, which last week suffered heavy losses when thousands of pagers and walkie-talkies used by its members exploded.
The operation was widely blamed on Israel, which has not confirmed or denied responsibility.
In another major blow, an Israeli airstrike on Beirut s southern suburb on Friday struck senior Hezbollah commanders, killing 45 people, according to the Lebanese health ministry.
The fighting has raised fears that the U.S., Israel’s close ally, and Iran will be sucked into a wider war.
Imad Kreidieh, head of Lebanese telecoms company Ogero, said more than 80,000 automated calls asking people to evacuate their areas had been detected on the network.
Lebanese information minister Ziad Makary said his ministry had received an Israeli call with an order to evacuate its building, but that it would not comply. "This is a psychological war," Makary told Reuters.
Suffering from a financial meltdown, Lebanon can ill afford another war like the one that erupted in 2006, when Israel pounded it during a month-long conflict with Hezbollah, inflicting heavy damage to infrastructure.
In the Beirut district of Sassine, state employee Joseph Ghafary said he feared Israel s strikes and Hezbollah retaliation would trigger a full-blown war.
"If Hezbollah carries out a major operation, Israel will respond and destroy more than this. We can’t bear it," he said.
"Israel wants to strike, it wants to keep going, meaning it is squeezing [Hezbollah leader] Sayyed Hassan [Nasrallah] to start a war."
Mohammed Sibai, a shopowner in the Beirut neighbourhood of Hamra, said he saw the escalation in strikes as "the beginning of the war".
"If they want war, what can we do?" he said. "We cannot do anything."