Activists use Facebook to call for mass demonstrations

Beirut  Activists called for mass anti-regime demonstrations in the Syrian capital Damascus Friday following deadly suicide attacks they said were perpetrated by the regime.

"Residents of Damascus, rise up, liberate your city from this regime of killers," said the The Syrian Revolution 2011 activist group on Facebook.

"The one that destroyed Homs and its residents with tanks and shells will not hesitate to destroy Damascus and to kill its residents with explosions.'

Relentless shelling

Rebel neighbourhoods of the central city of Homs came under relentless shelling by regime forces in March that left widespread destruction and hundreds dead, according to rights groups.

"The regime will not hesitate to kill all its people to attain its objective ... what are you waiting for!" added the message posted after at least 55 people were killed and nearly 400 wounded in the deadliest bombings of Syria's 14-month uprising.

Meanwhile, the US embassy in Beirut called the double bombing "reprehensible and unacceptable" but said it would not change US demands that the Syrian government implement a UN-backed peace plan.

Deadliest attacks since the uprising began

The bombings were the deadliest attacks since the uprising against President Bashar Al Assad began.

International envoy Kofi Annan condemned the blasts.

A statement issued by Annan's spokesman Ahmad Fawzi said he "condemns in the strongest possible terms the attacks that took place earlier today in Damascus".

The statement said: "He is saddened by the loss of life resulting from the two blasts and extends his condolences to the families of the victims. These abhorrent acts are unacceptable and the violence in Syria must stop."

The statement added that Annan "reiterates his call to all parties to adhere to the cessation of violence".

"Any action that serves to escalate tensions and raise the level of violence can only be counter-productive to the interests of all parties," the statement said.

"The Joint Special Envoy calls on all parties to avoid further bloodshed and to protect civilians. The Syrian people have already suffered too much."