A Palestinian camp official had told AFP earlier that an Israeli strike targeted the house of the son of a top Palestinian militant in the Ain al-Helweh camp on the outskirts of the southern city of Sidon.

"The Israeli raid targeted the house of the son of Mounir Maqdah" in the Ain al-Helweh camp, the official said, requesting anonymity to discuss sensitive matters.

It was unclear if Maqdah -- who Israel has accused of heading the Lebanese branch of Fatah's armed wing -- was at the property.

The official National News Agency said his son Hassan Maqdah, his wife and four other people -- a woman and three children -- had been killed.

The Israeli military in August said it had killed Mounir Maqdah's brother, Khalil Maqdah, described by Fatah as "one of the leaders" of its armed wing in Lebanon.

Israel had accused him of "directing attacks and smuggling weapons" to the Israeli-occupied West Bank, where Fatah is based.

The strike overnight is the latest targeting Palestinian armed group leaders or members in Lebanon.

The Popular Front for the Liberation of Palestine (PFLP), a secular left-wing group, said three of its members were killed in a strike on Beirut's Cola district early Monday.

Palestinian militant group Hamas said its leader in Lebanon was killed on the same day in an air strike on his "home in the Al-Bass camp in south Lebanon".

Early in August, an Israeli strike on a vehicle in Sidon killed Hamas commander Samer al-Hajj.