Lebanon's Hezbollah launched a barrage of more than 200 rockets and drones at Israeli army positions on Thursday as tensions soared amid the almost nine-month-old war raging in Gaza.

The Iran-backed militant group said its latest attack, which followed over 100 rockets fired the previous day, came in response to Israel's killing of a senior Hezbollah commander in south Lebanon.

Israel reported no deaths in its northern border area, where most communities have been evacuated, but quickly said it had responded with strikes in southern Lebanon.

Israel and Hezbollah, an ally of Palestinian militant group Hamas, have exchanged near daily cross-border fire since the Gaza war erupted on October 7, stoking fears of an escalation into all-out war.

UN chief Antonio Guterres voiced concern on Wednesday "about the escalation of the exchange of fire," his spokesman Stephane Dujarric said, warning of the risk to the wider Middle East "if we were to find ourselves in a full-fledged conflict."

Hezbollah and Hamas are part of an Iran-led "Axis of Resistance" against Israel and the United States, a regional alliance that also includes Yemen's Houthi rebels and armed groups in Iraq and Syria.

The Israeli military confirmed Hezbollah claims that over 200 rockets were launched on Thursday and said that its forces were "striking launch posts in southern Lebanon" in response.

Israeli air defences intercepted most incoming rockets, and the only reported casualty was a man slightly wounded by shrapnel, while some of the impacts sparked wildfires.

Israel killed senior Hezbollah commander Mohammed Naameh Nasser with a strike in the Lebanese coastal city of Tyre on Wednesday.

A source close to the group described him as "responsible for one of three sectors in south Lebanon." His death came after an Israeli strike in June killed Taleb Abdallah, who headed another sector.

Speaking at Nasser's funeral, top Hezbollah official Hashem Safieddine warned Israel against "imagining that targeting these heroes would ever leave the south exposed."

"When any leader becomes a martyr, another takes up the banner and proceeds with new, firm and strong resolve."

The Gaza war broke out after Hamas's October 7 attack on southern Israel resulted in the deaths of 1,195 people, mostly civilians, according to a tally based on Israeli figures.

The militants also seized 251 hostages, 116 of whom remain in Gaza including 42 the army says are dead.

Israel's retaliatory offensive has killed at least 38,011 people, also mostly civilians, according to figures from the Hamas-run territory's health ministry.

The Israel-Hezbollah border clashes have killed at least 496 people in Lebanon, most of them fighters but also including 95 civilians.

Israeli authorities say at least 15 soldiers and 11 civilians have been killed on their side of the UN-patrolled border. (AFP)