Casualties were reported along the Israel-Lebanon border Saturday as the army traded fire with Iran-backed militant group Hezbollah amid fears of a new front opening as Israel battles Hamas.

Israel already ordered the evacuation of Kiryat Shmona, a border town which is home to some 25,000 people, as the border area has come fire from Hezbollah and allied Palestinian factions.

In Lebanon, Hezbollah said one of its fighters had been killed while in Israel, two Thai farm workers were wounded, emergency services said.

A senior Hezbollah official warned that the movement stood ready to step up its involvement as Israel masses troops on the Gaza border, vowing to destroy Palestinian militant group Hamas in response to its shock cross-border attacks on October 7.

"Let's be clear, as events unfold, if something comes up that calls for greater intervention by us, we will do so," said Hezbollah number two Naim Qassem.

In northern Israel, a strike in the Margaliot area of the border wounded two Thai farm workers, Israel's Magen David Adom emergency medical service said.

One was wounded in the chest, the other sustained a limb injury, the service said.

There are around 30,000 Thai labourers in Israel, many working in the agricultural sector.

Since October 7, exchanges of fire across the border have killed at least four people in Israel — three soldiers and one civilian.

In southern Lebanon, at least 23 people have been killed. Most have been combatants, but at least four civilians, including a Reuters journalist, have also been killed.

Saturday's exchanges came as Israeli Defence Minister Yoav Gallant visited the northern border, where he called on troops to remain "vigilant".

"Hezbollah has decided to participate in the fighting, and is paying a price for it. We must be vigilant and prepare for every possible (scenario). Great challenges await us," Gallant said.

The Shiite Muslim Hezbollah movement, Lebanon's only armed faction that did not disarm after the 1975-1990 civil war, fought a devastating war with Israel in 2006.

That war left more than 1,200 dead in Lebanon, mostly civilians, and 160 dead in Israel, mostly soldiers, in a conflict that left the border bristling with guns.