Israeli air strikes have destroyed two bridges over the Litani River linking southern Lebanon with the rest of the country, the military says.
It comes hours after the Israeli military said it would target crossings it alleged were being used by the Hezbollah armed group to move fighters and weapons.
Elsewhere, Israeli strikes hit multiple locations in Beirut, killing at least 12 people and wounding 27, Lebanese authorities said. The escalation marks a widening of Israeli strikes beyond the southern suburbs into central Beirut.
The Lebanese health ministry says that 968 people, including at least 111 children, have been killed since 2 March.
Lebanon was drawn into the US-Israel war against Iran when Iran-backed Hezbollah fired missiles into Israel. Israel responded with air strikes and later sent ground troops into southern Lebanon.
Defence minister Israel Katz said the bridges were targeted on Wednesday in a 'direct action against Hezbollah's use of Lebanon's state infrastructure to advance terrorist activity.' Hezbollah has not yet commented.
Earlier on Wednesday, the Israeli military warned civilians near the Litani crossings to evacuate.
On Friday, the Zrarieh Bridge over the Litani was damaged in an Israeli strike.
The Litani River has long been central to Lebanon's fragile security landscape. Under UN Security Council Resolution 1701, which ended the 2006 war between Israel and Hezbollah, armed groups are barred from operating south of the river. Israel says Hezbollah maintains a significant presence there.
The latest Israeli warnings to evacuate have deepened an already severe displacement crisis. More than a million people have been forced to leave their homes, Lebanese officials say, mainly in the south and east of the country and southern Beirut, where Hezbollah's presence is strongest.
Overnight on Wednesday, Israeli strikes also hit the town of Zefta in the Nebatieh district, south of the river.
A group of men swept shattered glass from in front one of the collapsed buildings. A 25-year-old man said the strike had come without warning, and he after hearing a loud noise he had been thrown across the room by the blast.
'There's no one here related to a political party,' he said. 'We are all civilians, not affiliated with anyone.'
