A Palestinian militant group said on Monday that three of its leaders were killed in an Israeli strike on Beirut, the first attack within city limits as Israel escalated hostilities against Iran's allies in the region.

The Popular Front for the Liberation of Palestine (PFLP) said the three leaders were killed in a strike that targeted Beirut's Kola district.

The strike hit the upper floor of an apartment building in the Kola district of Lebanon's capital, witnesses said.