|Hundreds of Syrians fleeing fierce fighting in their homeland have crossed into Lebanon [Reuters]
At least 15 Syrian tanks have pushed into a rural area near the Lebanese border, where security forces have been concentrating their latest crackdown against pro-democracy demonstrations, human rights activists have said.
The activists, who said they were in contact with residents there, said the tanks deployed around Arida, near the Jisr al-Qomar border crossing point with northern Lebanon, on Monday.
Witnesses on the Lebanese side of the border told the Reuters news agency that they had heard the sound of gunfire throughout the night.
Activists said Syrian troops and armed men had entered the town of Talkalakh, also near the Lebanese border, on Saturday after protests erupted against the rule of Bashar al-Assad, the president.
An activists' protest group said at least seven Syrian civilians were killed on Sunday when troops shelled the town and sniper fire killed another civilian on Monday, raising the death toll from the army's assault, which began on Saturday, to 12.
The official Syrian state news agency said five soldiers had been killed in confrontations with armed groups in Talkalakh.
One resident said there was intermittent shelling and machine gun fire with heavy bursts on Talkalakh on Monday, but the army appeared not to have advanced beyond the town's outskirts.
"Talkalakh is a ghost town. There are no doctors. Pharmacies are shut. Snipers are on the roof of the main
hospital. Phones, water and electricity are cut," Mohammad al-Dandashi, a resident of the town, told Reuters.
Syrians fleeing their homeland described a "catastrophic'' scene on Monday in Talkalakh, which has been largely sealed off as the army tries to crush a two-month uprising.
"The situation ... is catastrophic,'' said Ahmad, 55, who crossed the border into Lebanon overnight Monday and asked to be identified only by his first name.
"If you walk in the streets of Talkalakh you can smell the dead bodies,'' he said.
Authorities justified the siege by saying the town was full of Islamic extremists who wanted to form an Islamic state, residents told the AP news agency.
One resident said the conflict in Talkalakh had taken on dangerous sectarian tones.
Hamid, 45, who also asked to be identified only by his first name, said pro-government armed men known as "shabiha'' were targeting Sunnis in the town.
Meanwhile, an activist told the AFP news agency that a mass grave was discovered on Monday in Daraa, the southern Syrian town at the heart of the protests.
"The army today allowed residents to venture outside their homes for two hours a day," Ammar Qurabi, of the National Organisation for Human Rights in Syria, said.
"They discovered a mass grave in the old part of town but authorities immediately cordoned off the area to prevent residents from recovering the bodies, some of which they promised would be handed over later," he said on the phone from Egypt.
He said he did not know how many people were buried in the mass grave.
Troops backed by armour have also deployed in or around towns and villages across the southern Hauran plain, the central province of Homs and areas near the coast.
The security grip has also been tightened in the capital, Damascus, and its suburbs.
Authorities have blamed most of the violence in the country on armed groups backed by Islamists and outside powers whom they say killed more than 120 members of the security forces.
Syrian and international rights groups say Syrian forces have killed at least 700 civilians since the unrest began.
Assad has tried a mixture of reform and repression to stem protests against his 11-year rule, which broke out in Deraa, inspired by uprisings across the Arab world.
Authorities said Assad intends to launch national dialogue talks, a gesture rejected by opposition leaders and the main activists' protest group, who say first security forces must stop shooting protesters and political prisoners must be freed.
More than 5,000 Syrians have fled to Lebanon in recent weeks as Assad's security forces try to crush the uprising against his government.