Syrian security officials inspect the site of an explosion in Damascus
Twin blasts hit the heart of Damascus on Saturday, killing at least 27 people in an attack on security installations that state television blamed on "terrorists" seeking to oust President Bashar al-Assad.
Syrian television reported that cars packed with explosives had targeted an intelligence centre and a police headquarters at 7.30 am (0530 GMT), blowing the front off one building and sending debris and shattered glass flying through the streets, reports Reuters.
Gruesome images from the sites showed what appeared to be smouldering bodies in two separate vehicles, a wrecked minivan smeared with blood, and severed limbs collected in sacks.
At least 27 people were killed and 97 were wounded, another television channel said, quoting Health Minister Wael al-Halki.
"We heard a huge explosion. At that moment the doors in our house were blown out ... even though we were some distance from the blast," one elderly man, with a bandage wrapped round his head, told a public television channel.
No one claimed responsibility for the coordinated detonations, which echoed similar attacks that have struck Damascus and Syria's second city Aleppo since December.
The explosions came just two days after the first anniversary of the uprising, in which more than 8,000 people have been killed and about 230,000 forced to flee their homes, according to United Nations figures.
They also coincided with a joint mission by the Syrian government, the United Nations and the Organisation of Islamic Cooperation that was due to start assessing humanitarian needs in towns across Syria which have suffered from months of unrest.
One source involved in the mission said team members were still gathering in Syria and it was not immediately clear if they would begin their work this weekend as previously planned.
The U.N.-Arab League envoy for Syria, Kofi Annan, warned on Friday that the crisis could spill over into other neighbouring countries and urged international powers to lay aside their differences and back his peace initiative.
While the West and much of the Arab world have lined up to demand that Assad steps down, his allies Russia, China and Iran have defended him and cautioned against outside interference.
"The stronger and more unified your message, the better chance we have of shifting the dynamics of the conflict," an envoy said, summarizing Annan's remarks to a closed-door meeting of the 15-nation Security Council.
Turkey said on Friday it might set up a "buffer zone" inside Syria to protect refugees fleeing Assad's forces, raising the prospect of foreign intervention in the revolt, although Ankara made clear it would not move without international backing.
Television showed numerous men and women receiving hospital treatment for multiple wounds following Saturday's strikes. Syria's Sana news agency said the blasts had hit the criminal police force headquarters and the Air Security Directorate.
The attacks followed three suicide bombings in Damascus in December and January which killed at least 70 people, and an attack in Aleppo in February that killed 28.
Al Qaeda leader Ayman al-Zawahri, in a video recording posted on the Internet last month, urged Muslims around the region to help Syrian rebels.
Syria has previously blamed al Qaeda for at least some attacks on its territory and vowed to respond with an iron fist.