Published: Nov 17, 2013 8:03 AM EST

   
BEIRUT (AP) - Thousands of refugees are fleeing border towns in central Syria where a high-stakes battle is raging, crossing valleys and ridges to reach safety in neighboring Lebanon, witnesses and the U.N. said on Sunday.
    
They packed into wedding halls and drifted into makeshift shacks after escaping the steadily intensifying fighting battle that began on Friday, said Bassel Hojeiri, former mayor of the border town of Arsal where most of the refugees have headed.
    
A Syrian government offensive in the rugged Qalamoun hills, which stretch from Damascus to Lebanon, seeks to cut rebel supply lines to opposition-held enclaves around the capital.
    
Activists and analysts say the battle may be the final blow that dislodges rebels from the Damascus periphery, where food is running short and opposition fighters have lost a series of strongholds in recent weeks to forces loyal to Syrian President Bashar Assad.
    
Former mayor Hojeiri estimated some 10,000 people had fled to Arsal, saying an influx of Syrians during the past three years of conflict had caused the population to nearly double.
    
Dana Sleiman of the United Nations High Commission for Refugees put the total number of refugee arrivals over the weekend at around 1,000 families. She said many had not registered yet with the U.N. and so they could not provide more definite numbers.
    
The UNHCR's Sleiman said refugees weren't able to reach an official border crossing because of the fighting, which began on Friday. Some families were in such a hurry that they could not collect any belongings before they fled, arriving "without anything except the clothes on their backs," she said.
    
The U.N. was distributing blankets, mattresses, food, nappies and hygiene kits to the refugees. She said some were settling into tin shack slums that dot eastern Lebanon's Bekaa Valley, and they were being offered thick plastic to reinforce their feeble homes against the cold.
    
Syrian refugees have overwhelmed Lebanon since the uprising began three years ago. Lebanese officials estimate there are 1.4 million Syrians in the country, including 800,000 registered refugees.
    
The battle for Qalamoun has been expected for weeks, with both government and opposition reinforcing their positions in the sector ahead of winter when much of the area is covered with snow.
    
Activists say one of the main sites of the battle is around the town of Qara, which lies near a main highway leading from Damascus to the central city of Homs. Controlling the region thus makes it easier to assert control over movement down the length of Syria.
    
On Sunday, two pro-rebel activist groups and the British-based Syrian Observatory for Human Rights reported two airstrikes hitting the town. They said highway was severed and regime forces had gathered on nearby hills, trying to cut supplies to rebels inside the city.
    
Syria's pro-government media vowed the battle would be decisive.
    
"The army is shaking Qalamoun Mountains and has tightened its siege around terrorists in Qara," read a front-page article in the al-Watan newspaper.
    
Mortar fire meanwhile hit the center of Damascus, killing two, the Syrian official news agency SANA said.