At least 48 people have been killed in bombings in mainly government-held areas of Syria, and dozens have been injured.
The Britain-based Observatory, which maintains a network of contacts in Syria, put the overall death toll at 53, although Syrian state TV said 48 were killed.
4 attacks took place within an hour in Tartous, Homs and in a suburb of Damascus, with one in Hassakeh, which is dominated by Kurdish forces.
The deadliest incident was outside Tartous, home to a Russian naval base and in the heartland of President Bashar al-Assad's Alawite sect.
The Islamic State group said it was behind the attacks.