Hassan Nasrallah says Hezbollah has 100,000 fighters
Hassan Nasrallah accused the Lebanese Forces, a Christian party, of being behind the killing of seven members of his movement and Shiite ally Amal at a rally on Thursday and warned it against sparking any "civil war".
He said he revealed for the first time how many fighters were in his ranks "to prevent war, not threaten a civil war".
Nasrallah spoke as tensions simmer in Lebanon over the fate of the judge leading a probe into a huge port explosion last year that killed more than 210 people, wounded thousands and wrecked swathes of Beirut.
Violence broke out in the heart of Beirut Thursday after supporters of Hezbollah and Amal rallied to call for judge Tarek Bitar to step down.
Hezbollah and Amal have accused Lebanese Forces snipers of starting the fight.
But Lebanese Forces leader Samir Geagea has denied this and said on Friday that residents of the Christian neighbourhood of Ain al-Remmaneh had "defended" themselves against "Hezbollah militiamen who tried to enter their homes".
The street violence left school children cowering under desks and adults hiding inside their homes for hours, for many reviving memories of street battles during the 1975-1990 civil war.
Hezbollah is the only side not to have disarmed after that conflict.
It is blacklisted by the West, but its political branch hold seats in parliament and considerable weight in Lebanese politics.