Hezbollah, a Hamas ally, has traded near daily cross-border fire with Israeli forces since the Palestinian group's October 7 attack on southern Israel that sparked the war in Gaza.
The source close to Hezbollah told AFP that "at least four Hezbollah fighters were killed in Israeli raids on two different sites in southern Lebanon", identifying the locations as Naqura on the coast and Mais al-Jabal, a border village to the east.
A Hezbollah fighter was also killed Monday in a strike in neighbouring Syria blamed on Israel, a separate source from the group told AFP.
The Shiite Muslim movement said five of its fighters, including two from Naqura, had been killed, without providing details on where or when they had died.
Lebanon's official National News Agency (NNA) later reported "one martyr and one wounded" after an "enemy airstrike targeted a motorcycle" in the village of Mansouri near the coast.
No further details were provided.
The Israeli military meanwhile said a soldier was "lightly injured" by "a launch that fell in the area of Biranit".
It later said it "struck a Hezbollah launcher" near Aita al-Shaab in southern Lebanon, "from which the launches were identified".
The army had earlier said fighter jets struck "a Hezbollah terrorist cell" and a launch post in the Mais al-Jabal area, while Israeli army "artillery fired to remove a threat" in the Naqura area.
Hezbollah said it launched a heavy rocket attack at an Israeli army barracks in the country's north "in retaliation" for the Naqura strike, while also announcing other attacks on Israeli positions.
NNA had reported Israeli strikes on Mais al-Jabal and Naqura, where it said Israel fired near Hezbollah-affiliated rescue personnel and wounded a civilian.
The fighting has killed at least 426 people in Lebanon, mostly militants but also including 82 civilians, according to an AFP tally.
Israel says 14 soldiers and 11 civilians have been killed on its side of the border.
The violence has raised fears of all-out conflict between Hezbollah and Israel, which went to war in 2006.
