Syrian state television claims that a pro-government group has hacked into two social messaging networks and seized records of local users.
Such a hack could expose Syrian rebels and other activists who depend on the networks to publicize army crackdowns on their hometowns and communicate with each other. Landlines and cell phones are believed to be tapped in Syria.
State TV says the social networking site Tango was hacked on Sunday by the Syrian Electronic Army.
The Syrian Electronic Army is a shadowy group that supports President Bashar Assad's regime.
There was no immediate comment from Tango.
Syrian media says another network – Truecaller - also was hacked last week.
Truecaller said in a statement posted on their website that it had been the target of a cyber-attack.
Syria: Pro-Assad group hacks messaging networks