Lebanese troops deployed in the northern city of Tripoli early on Sunday after fierce clashes between supporters and opponents of Syrian President Bashar al-Assad in which 13 people were killed, local medics and security sources said.
Residents said relative calm had returned to the city since the soldiers deployed at around 7am, after gunmen exchanged heavy machinegun fire and rocket propelled grenades.
Prime Minister Najib Mikati and other Tripoli politicians instructed security forces on Saturday to use an "iron fist" to quell the worst violence to shake Tripoli since the start of an uprising against Assad in neighbouring Syria.
The mainly Sunni Muslim protests against Assad have polarised Tripoli, where a small community of Alawites - from the same offshoot of Shi'ite Islam as Assad - have frequently clashed with majority Sunni Muslims who support the uprising.
The latest clashes began after midnight on Friday and continued throughout Saturday until the army deployment.