Lebanese troops have fired in the air to disperse dozens of Sunni Muslims demonstrating in support of a hardline cleric who has been on the run since the military crushed his fighters earlier this week.

The military moved to break up the demonstration in the southern port city of Sidon after protesters tried to reach the mosque complex where cleric Ahmad al-Assir used to give his sermons.

The compound has been under army control since Monday following two days of fighting between troops and al-Assir's followers that left dozens of people dead.

The demonstration started after thousands attended Friday prayers in a mosque in the city center.

Al-Assir's rapid rise in popularity among Sunnis underscores the deep frustration of many Lebanese who resent the influence Shiites have gained in government.