An airstrike has leveled an apartment building and killed three Palestinian militants in central Beirut, as Israel appeared to send a clear message that no part of Lebanon is out of bounds.

A blast in the Cola neighborhood was the first known Israeli strike in the central part of the city since a war with Hezbollah in 2006.

Israel has been carrying out air strikes across Lebanon for days, but Sunday's strike on Kola was the first to hit the heart of the capital Beirut. Four people were killed and a further four were injured in the attack, Lebanon's health ministry said.