Beirut - Syrian television said two "terrorist" explosions targeted an army staff building in the capital Damascus on Wednesday.
It said a fire broke out in the Umayad Square where the building is located.
The television said the explosions were the work of "terrorists" - a term the authorities use to refer to insurgents waging a violent uprising to oust Syrian President Bashar Assad.
On Tuesday Syrian insurgents detonated bombs at a building occupied by pro-government militias in Damascus.
Activists say more than 27 000 people have been killed in the 18-month-old uprising against Assad.
Syria's conflict, once a peaceful protest movement, has evolved into a civil war that the UN special envoy to Syria, Lakhdar Brahimi, said was "extremely bad and getting worse". He said the stalemate in the country could soon "find an opening", without elaborating.
Call for protection of rebel areas
Even Damascus has become a battleground between Assad's forces and opposition fighters.
With no foreseeable prospect of foreign intervention and diplomacy stuck, outgunned rebels have relied increasingly on attacks with homemade bombs, striving to level the playing field against a state using fighter jets, artillery and tanks.
At the annual UN General Assembly in New York, French President Francois Hollande sought to shake up international inertia over Syria's crisis by calling for UN protection of rebel-held areas to help end Syria's bloodshed and rights abuses.
The United States, European allies, Turkey and Gulf Arab states have sided with the Syrian opposition while Iran, Russia and China have backed Assad, whose family and minority Alawite sect have dominated the major Arab state for 42 years.
Humanitarian conditions are worsening as the violence drags on. The president of the Syrian Arab Red Crescent, which has been the only relief group on the ground the entire 18 months of conflict, said it was in dire need of supplies.