Israel's military said it again attacked targets of the Iranian-backed Hezbollah militia in the Lebanese capital Beirut on Sunday, with witnesses reporting five heavy bombardments in the southern suburbs of Dahiyeh.

Lebanon's Health Ministry reported four dead and dozens injured. Lebanon's state-run National News Agency (NNA) and eyewitnesses said a three-storey building was hit.

The first wave of attacks began shortly after midnight (2100 GMT Saturday), according to eyewitnesses. Plumes of smoke were repeatedly seen rising in the area.

The wounded were being carried out with blankets as no stretchers were available, according to a dpa witness at the scene of one attack on the Shiite neighbourhood of Jnah near Rafik al-Hariri Hospital.

The area is considered a Hezbollah stronghold but is also a densely populated residential district. Israel's military has repeatedly called on residents there to flee.

Elsewhere, six people were reported killed in Israeli airstrikes in southern Lebanon, NNA reported earlier Sunday.

NNA reported the deaths in the town of Kfar Hatta, saying they were members of a displaced family.

In another airstrike, also in southern Lebanon, at least three people were killed and others injured early on Sunday morning, the news agency reported separately.

The information could not be independently verified.

Israel's military initially did not comment on the reports when asked.

Besides attacking Lebanon from the air, it is also conducting ground operations against the Iranian-backed Hezbollah militia in neighbouring Lebanon.

Meanwhile, the Hezbollah again fired projectiles at northern Israel. In an area in Galilee, there were repeated rocket alerts early Sunday afternoon. Warning sirens also sounded in other parts of the north of the country after shelling by the Lebanese militia.

There were initially no reports of damage or casualties.