Violence from Syria had spilled over the border into northern Lebanon last week, pitting pro- and anti-Syrian neighborhoods against one another.
Syrian forces played a dominant role in Lebanese affairs until the Cedar Revolution in 2005 loosened the grip of Damascus following 15 years of civil war.
The National News Agency of Lebanon reports that clashes between rival political forces left two people dead and 18 injured in overnight fighting. Heavy machine gun fire was reported during the weekend in Beirut.
U.N. special envoy for Lebanon Derek Plumbly said he was "very concerned" about the escalating violence in Lebanon, The Daily Star newspaper in Lebanon reports.
"I am confident now that all parties in Lebanon will continue to put the interests of the country above other considerations," he was quoted as saying. "Differences must be addressed through dialogue, not [a] resort to violence."
The Syrian Embassy in Beirut reportedly issued a travel warning advising against travel to the country given the recent outbreak of violence.
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