Israel has launched air strikes in Lebanon and is restricting gatherings in the city of Haifa and other northern areas as it continues to attack targets linked to Hezbollah.

Dozens of fighter jets started “extensively” striking southern Lebanon “following detection of Hezbollah preparing to fire toward Israeli territory”, Israel Defense Forces (IDF) spokesman Rear Adm Daniel Hagari said.

The latest Israeli offensive comes a day after it carried out an air strike in Beirut, which the IDF said killed a dozen senior Hezbollah commanders. Lebanon said 37 people – including three children – were killed.

The US government is urging its citizens there to leave “via commercial options while still available”.

On Friday, exchanges of cross-border fire resumed between Israel and Hezbollah.

Before the evening Israeli strikes began, the IDF said earlier it had destroyed “about 180 sites and thousands of [rocket] launcher barrels” with strikes

The IDF also said more than 90 rockets were fired at Israeli territory from Lebanon. Hezbollah said it had targeted 11 Israeli military positions over the course of the day.

Earlier this week, 39 people were killed and thousands wounded after pagers and walkie-talkies used by Hezbollah, the Iranian-backed militia and political group, exploded on two days across Lebanon.

On Thursday, Hezbollah leader Hassan Nasrallah blamed Israel for the attacks, saying it had crossed “all red lines” and vowed “just punishment”.

Israel has not claimed responsibility.

UN human rights chief Volker Türk said the pager and walkie-talkie explosions violated international humanitarian law.

On Saturday, the IDF announced new restrictions on communities in northern Israel and parts of the southern Golan Heights starting at 20:30 local time (17:30 GMT).

The IDF limited gatherings to 30 participants in an open area and 300 participants in a closed space. Educational activities can continue and arrival to work is permitted as long as there are protected spaces available.

The restrictions apply to the Haifa area and northward.

As fears increase that the conflict may break out into a full-scale war, the US State Department issued new travel advice for citizens currently in Lebanon.

The US Embassy in Beirut urged people to “depart Lebanon while commercial options still remain available”, noting they were already running at “reduced capacity”.

The embassy added it “may not be able to assist US citizens who choose to remain”.

Neighbouring Jordan’s foreign ministry issued similar advice to its citizens, urging those in Lebanon to leave as soon as possible.

Cross-border fighting between Israel and Hezbollah escalated on 8 October 2023 – the day after the attack on Israel by Hamas gunmen from Gaza – when Hezbollah fired at Israeli positions in solidarity with the Palestinians.

Israel recently added the return of people displaced from the north of the country due to the cross-border fighting to its list of war goals.

Defence Minister Yoav Gallant said on Thursday that Israel was entering a “new phase of the war” concentrating more of its efforts in the north.