At least 16 soldiers were killed on Saturday during an assault on a checkpoint in a pro-government Damascus suburb, activists reported.
The Britain-based Syrian Observatory for Human Rights said a suicide bomber detonated the car bomb in an attempt to capture the checkpoint between the rebel-held town of Mleha and pro-regime suburb Jaramana, which is populated by Christians and Muslim Druze. The monitoring group said heavy fighting ensued.
It claims the al Qaeda-linked Islamist group Jabhat al-Nusra, or Nusra Front, was behind the attack.
Syrian state news agency SANA confirmed several casualties following the blast in Jaramana, although it did not provide a precise death toll.
The attack comes hours after rebels released nine Lebanese hostages held since their capture in Syria's northern Aleppo province in May 2012.
According to UN figures more than 100,000 people have been killed in the Syrian conflict since it erupted in March 2011.
ccp/tj (AFP, Reuters, AP)