Dozens of people have been killed by Israeli strikes in Lebanon, including 20 who died after a strike flattened a multi-story residential building in central Beirut overnight, according to Lebanese officials.

An Israeli airstrike killed at least 20 people in central Beirut on Saturday, Lebanon's health ministry said, one of the deadliest strikes on the heart of the capital since Israel began its assault against the Iran-backed Hezbollah group in September.

Muhammad Haydar's fate unclear; overnight strike not preceded by evacuation orders, comes as rockets trigger sirens around Haifa, with impact in Kiryat Ata