BEIRUT -- A U.S.-based firm that monitors online activity has confirmed a "largely complete" restoration of Internet service in Syria following a two-day, nationwide blackout.

Renesys, which studies Internet disruptions, said in a statement Saturday that service went back up around 4:32 local time in Syria.

The communications blackout began Thursday, raising fears of a burst of fighting outside the public eye. The government and rebels have blamed each other for cutting the lines.

Syrian troops are fighting a 20-month-old revolt against the President Bashar Assad's regime. Activists say some 40,000 people have been killed in the violence.