Israel bombed central Beirut in the early hours of Thursday, killing at least six people, after its forces suffered their deadliest day on the Lebanese front in a year of clashes against Iran-backed armed group Hezbollah.

Israel said it conducted a precise airstrike on Beirut.

Reuters witnesses reported hearing a massive blast, and a security source said it targeted a building in central Beirut's Bachoura neighborhood close to parliament, the nearest Israeli strikes have come to Lebanon's seat of government.