Activists say Syrian military and security forces have deployed heavily in Damascus ahead of planned protests against President Bashar Assad's rule.
The weekly protests following Friday prayers are gaining momentum.
Syrian security forces killed 32 people last Friday during the largest protests since the uprising began more than four months ago. Around half of those were in killed in Damascus.
The Syrian Observatory for Human Rights said security forces deployed heavily in the Qaboun and Rukneddine neighborhoods of Damascus Friday.
It said the troops carried out patrols and set up checkpoints at entrances. They also conducted raids on homes and made many arrests.