International envoy Kofi Annan says the 16-month conflict in Syria has reached a critical point as heavy fighting in the capital Damascus enters a third straight day.
Syria's rebel army says it has launched a full scale offensive to "liberate" the capital, dubbing the campaign "the Damascus volcano and earthquakes of Syria."
Fighting in the capital appears to be worsening, with reports that government forces are deploying tanks and helicopter gunships as they fight to regain control of rebel-held areas.
The clashes have now reached Sabaa Bahrat Square - a central site where President Assad's regime once staged pro-government rallies to counter the opposition protests that erupted early last year.
"There is no going back. The Damascus battle has priority for us. We have started the operation to liberate Damascus," rebel commander Colonel Qassem Saadeddine said.
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