Thousands of Syrian refugees have poured into Lebanon over the past two days as fighting between government forces and rebels has flared near the border, Lebanese officials said Saturday.
The refugees were fleeing the Qalamoun mountains north of Damascus, a strategic border district with a mixed Sunni Muslim and Christian population where both sides have been massing forces.
Lebanon already hosts more than 814,000 Syrian refugees, and recent clashes between Lebanese factions split over the war in neighbouring Syria have raised fears the conflict could spill across the border.
"Starting Friday night, a large number of Syrian refugee families fled to the eastern Bekaa region, notably to Arsal, where 1,200 families took shelter," Lebanon's social affairs ministry said.
The ministry statement said most of the families were coming from Qalamoun and Homs province, and that the Lebanese authorities and the United Nations were working to accommodate them.
Ahmad al-Hojairi, a local official, had earlier told AFP that most of the families had come from Qara village in Qalamoun, crossing the border by car, by motorbike or on foot.
The Lebanese army, meanwhile, said it had arrested nine Syrians in the area of Arsal and the eastern Baalbek region, adding that they were carrying small arms and explosives.
Rami Abdel Rahman, the head of the Syrian Observatory for Human Rights, a Britain-based monitoring group, said the Qalamoun area was "witnessing the lead-up to a major battle".
Signup to our newsletter and follow us on Facebook and Twitter!
Residents on the Lebanese side of the border said they heard the sound of heavy shelling from the Syrian side throughout Friday.
After months of being largely spared the violence tearing apart other areas of Syria, parts of Qalamoun have faced nearly-daily shelling in recent weeks.
A Syrian security source told AFP the fighting in Qara was the result of an attempt by the army "to chase down the terrorists who fled from Mahin".
Mahin, in adjacent Homs province, is the site of a major weapons depot. The army announced it had recaptured the town on Friday after weeks of fighting.
Farther north, troops pressed an offensive to consolidate their supply lines to Syria's second city Aleppo, which is split into regime- and rebel-held areas.
"Most of the road linking Sfeira to Aleppo city is in regime hands," said the Observatory's Abdel Rahman.
In the capital, shelling of the government-held Kassaa and Abbasiyeen neighbourhoods killed one woman, the Observatory said.
More than 120,000 people have been killed in Syria since an uprising against President Bashar al-Assad's rule erupted in March 2011.