"He has a pulse. He has a pulse," one teenager shouts next to the blood-soaked body of a youth in jeans. "No, no. Martyr. Martyr," he says as his comrades rush to carry the body under a hail of machinegun bullets.

The footage was believed to have been taken on Friday in the southern city where protests broke out in March, the start of a six-week-old uprising against President Bashar Assad. Troops and tanks stormed into Deraa on April 25.

More footage shows a similar scene at a road leading to Daraa, where young villagers on motorcycles rushed on Friday to support their relatives under the week-long siege.

"God is greatest. Down with Bashar," the villagers chant as a hail of bullets hits the crowd. A youth falls down with a bullet in his back.

"Say the shahadah," whispers one youth in the ear of a comrade, referring to the Muslim declaration "There is no God but Allah.”

Foreign correspondents have largely been excluded from Syria since a government crackdown began, and Reuters was not able to verify the content of the videos independently.

But the smuggled material appeared to support witnesses' and rights groups' accounts of dozens of civilians killed by live fire from snipers, security forces and an army unit commanded by Assad's feared brother Maher.

After a six-day campaign in which Assad sent dozens of tanks and armored vehicles into the center of the old city in the fiercest assault on the pro-democracy uprising, witnesses recounted an eerie silence on Sunday in the area, replacing days of heavy shelling.