The Syrian army has launched renewed assaults on several cities including Homs and Hama, killing dozens of people, according to activists.
Most of the deaths have occurred in Homs, rights groups say. The Arab League says there has been a "high escalation" of violence in recent days.
The BBC's Jeremy Bowen in Damascus says the regime appears to be losing control of rebellious areas of the capital.
The UN Security Council is due to discuss a possible resolution on Syria.
Anchor Lisa Mullins gets the latest from the BBC's Lina Sinjab.
Syrian troops are deployed in a Damascus suburb as tension mounts.