At least 52 people have died in clashes and bombing across Syria, with activists calling for another day of protests as the uprising against President Bashar al-Assad enters its 16th month.
Fourteen people were also wounded when a suicide bomber blew up a vehicle near an important Shi'ite Muslim shrine in the capital on Thursday.
Another car bomb in the northwestern city of Idlib killed and wounding a number of soldiers, the Syrian Observatory for Human Rights said.
Monitors say more than 14,100 people, mostly civilians, have died since a peaceful uprising erupted on March 15, 2011, prompting a bloody crackdown by Assad's forces that prompted an armed reaction.
More than 2302 have reportedly died in the past month alone.
Official news agency SANA said a vehicle in Damascus exploded in a garage 50 metres from the shrine and caused substantial damage, with the "terrorist" who launched the operation killed.
The Observatory, citing anti-regime activists, said it went off near security offices, damaging the apparent target as well as the shrine, as seen in a video posted on the internet.
Most of Syria's 22 million population are Sunni Muslims, while its minorities include Alawites, an offshoot Shi'ite community to which Assad belongs.
As the death toll soars, Amnesty International accused the Syrian regime of committing crimes against humanity to punish communities supporting rebels.
The London-based group called for an international response, saying it had fresh evidence victims, including children, had been dragged from their homes and shot dead by soldiers, who set some bodies on fire.
"This disturbing new evidence of an organised pattern of grave abuses highlights the pressing need for decisive international action," said Amnesty's Donatella Rovera on the release of the 70-page report entitled Deadly Reprisals.
Meanwhile, UN observers visited Al-Haffe town in Latakia, a day after Syrian authorities said the area had been "cleansed" of rebel fighters after intense regime shelling for eight days.
The UN Supervisory Mission in Syria said the observers reported finding it all but deserted with a strong stench of dead bodies and most state buildings gutted.
