Syrian troops on Wednesday forced the rebel Syrian Free Army from one of its strongholds near the border with Iraq and took control of the area, activists said, dpa reported.
"The Syrian Free Army withdrew from Deir al-Zour to avoid a civilian massacre at the hands of the regime forces," the opposition group, which is made up of army defectors, said in a statement.
Deir al-Zour is the third rebel stronghold to fall to the government forces this month. Last week, troops took control of the dissident city of Idlib near the border with Turkey.
On March 1, government forces captured the opposition bastion of Baba Amr in the central province of Homs after almost a month of bombardment, according to activists.
Syria's official news agency SANA said Wednesday an unspecified number of security personnel were killed overnight in a suicide attack in the southern province of Daraa.
Meanwhile, activists residing on the outskirts of the capital Damascus said people were fleeing the area for fear that the government will launch an offensive "very soon."
"Many residents of areas in Reef Damascus have left their houses, heading for eastern Lebanon," Haytham al- Abdallah, an activist told dpa by phone.
A Lebanese security source, who requested anonymity, told dpa that five families had arrived in Lebanon "through legal passageways overnight."
Violent clashes took place between government forces and army defectors on the outskirts of Damascus, according to the opposition Syrian Observatory for Human Rights.
Heavy machine guns were used in the fighting that occurred near an intelligence service centre, the London-based group said.
The United Nations estimates that more than 8,000 people, mainly peaceful protesters, have been killed in Syria since the uprising against the rule of President Bashar al-Assad started in mid-March, 2011.