At least 10 people have died in north Lebanon in two days of gun battles between supporters and opponents of Syrian President Bashar al-Assad.
Clashes in the port city of Tripoli also left 49 people wounded including 11 soldiers, a security source said.
Tripoli, with a small Alawite community surrounded by a Sunni majority, is seen as one of Lebanon’s most volatile sectarian fault-lines.
President Assad is an Alawite and is fighting a Sunni-led revolt.
Correspondents say tensions have been high since last week, when residents of the Alawite district of Jabal Muhsin began flying Syrian flags in support of President Assad.
In response, residents of neighbouring Bab al-Tabbana raised the flag favoured by Syrian rebels.
Clashes broke out on Saturday, leaving at least six dead, and continued into the night.
On Sunday, at least four people were hit by sniper fire, including an off-duty soldier and two people in a lorry.
The Lebanese army remained deployed in the area on Sunday and a military source said four people had been arrested.
Clashes intensified on Sunday night and the government news agency said many of the city’s schools would be closed on Monday.
Shia Islamist militant group Hezbollah, which has fought on the side of pro-Assad forces in Syria, denied reports that it had sent fighters and military experts to Jabal Muhsin.
On-off fighting between the two districts has claimed scores of lives over the past two years.