The TV said the explosion took place near a parking lot used by the army command, which is about 300 meters (yards) away.
- Former PM: Assad only controls 30% of Syria
- Syrian envoy: We're at war with Tel Aviv
- Syria's UN human rights envoy defects
The Free Syrian Army has claimed responsibility for the attack, according to Al-Arabiya. Lieutenant Abu al Nour said the headquarters had been completely destroyed while some 150 people were inside, and that none so far had exited the building.
Syrian Deputy Foreign Minister Faisal Mekdad toured the area of the blast and said none of the UN staff was hurt. The explosion occurred as UN humanitarian chief Valerie Amos was in the Syrian capital but her team is believed to be staying at a different hotel.
Smoke fills Syrian capital after blast (Photo: AFP)
According to an Associated Press reporter at the scene, the blast had gone off inside a different parking lot, one belonging to a military compound and not the military command. The lot is near the Dama Rose Hotel, popular with the UN observers in Syria.
The hotel was slightly damaged in the blast, with some of its windows shattered. A Labor Union building across from the hotel was also damaged and black smoke was seen billowing into the sky before the fire was extinguished.
Several fire engines arrived shortly after the morning blast to fight the blaze. The fire was extinguished less than an hour after the explosion.
UN officials in Damascus had no immediate comment when contacted by the AP.
"This is a criminal act that shows what kind of attacks Syria is being subjected to," Mekdad told reporters at the scene. "Such explosions will not affect Syria."
"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," he added.
Wave of explosions
Damascus has been hit by a wave of explosions in the past months and clashes between government troops and rebels have also recently reached the capital, which had been relatively quiet since an uprising against President Bashar Assad's regime started in March last year.
Activists say more than 20,000 people have been killed since then, and the conflict has morphed into a full-out civil war.
"Those who carry out such terrorist attacks are destroying their country in order to get some pounds," shouted Ali Mohammed Ismail, 48, who said he happened to be in the area when the explosion occurred.
Roi Kais contributed to this report
- Receive Ynetnews updates
directly to your desktop