Three people were injured when a car bomb went off on Wednesday near a hotel in central Damascus used by the UN monitoring mission in Syria, Al Jazeera said, quoting Syrian state TV.
The bomb went off in the Abu Remanih area which is also the location of a military depot and the trade union headquarters, the report said. The Syrian military's Central Security Command is also located nearby.
Several ambulances rushed to the scene and police cordoned off the area.
The head of the UN observer mission in Syria, General Babacar Gaye, had held a press conference on Monday in the hotel, the Dama Rose, the report said.
Al Jazeera quoted a spokesperson for the opposition Local Coordination Committees in Damascus as saying a series of smaller explosions preceded a bigger one.
The UN was not immediately available for comment. Faisal Mekdad, the Syrian deputy foreign minister who toured the area shortly after the blast, said none of the UN staff was hurt.
"This is a criminal act that shows what kind of attacks Syria is being subjected to," Mekdad was quoted as telling reporters at the scene. "Such explosions will not affect Syria."
The blast struck on the eve of a UN Security Council meeting on Thursday in which the council will discuss the future of the UN observer mission in Syria, whose mandate expires on August 19.
"I confirm that we are with the UN and we will do all we can to guarantee their protection so that they carry out their role," Mekdad said.
The explosion occurred as UN humanitarian chief Valerie Amos has arrived in Syria to discuss ways of getting aid to people caught up in the conflict.
