Clashes in Lebanon's capital Beirut and the northern city of Tripoli have left seven people dead and dozens more injured as the army warned of "unprecedented" tensions in the country.
The military are lining the streets of the capital in a bid to force gunmen off the streets and quell the violence as fears grow that Syria's civil war could spill over the border.
Unrest began on Friday after a senior intelligence chief was murdered in a car bomb, an attack many see as being orchestrated by Syrian elements.
Security official Wissam al-Hassan had recently helped to bring about the arrest of one of Syria's top allies in Lebanon on suspicion of planning to carry out terrorist attacks.
Violence erupted following the funeral of al-Hassan on Sunday after security forces clashed with protesters angry at Syria's perceived role in the killing.
Lebanese soldiers fired bullets in the air and launched tear gas at mourners as protesters tried to storm a government office demanding the resignation of Prime Minister Najib Mikati.
In a statement on Monday, the army said: "The country is going through a decisive and critical time and the level of tension in some regions is rising to unprecedented levels".
It warned "all political leaders to be cautious when expressing their stances and opinions.. because the fate of the nation is at stake" reported the BBC.