The blast, which occurred on Monday, targeted a building in the heart of Salmiyeh and left 30 people dead and many others injured, AFP reported.
Medical sources say they expect the death toll to rise to well over 50, adding that some of the injured are in critical condition.
There has been no letup in the fierce clashes between Syrian security forces and foreign-backed militant groups.
Meanwhile, the leaders of the so-called Syrian National Council were unable to form a “transitional government” at a meeting in Istanbul on Monday.
On January 6, Syrian President Bashar al-Assad stated that Damascus was always ready to hold talks with the opposition and political parties and that he would call for a “comprehensive national dialogue” after the terrorist activities stopped.
The Syrian president also urged “concerned states and parties” to stop funding, arming, and harboring militants.
Syria has been experiencing unrest since mid-March 2011. Many people, including large numbers of security personnel, have been killed in the violence.
The Syrian government says the chaos is being orchestrated from outside the country, and there are reports that a very large number of the militants fighting the Syrian government are foreign nationals.
And several international human rights organizations have accused the foreign-sponsored militants of committing war crimes.