Renewed violence across Syria has left dozens dead, as Arab League observers continue their mission to oversee a peace plan for the country.
In the capital Damascus, state TV said up to 26 people died when a suicide bomber detonated explosives near a bus.
Opposition groups say the government staged the blast to influence the Arab League mission.
Elsewhere in Syria, activists say 29 people have been killed by security forces during anti-government protests.
The Damascus blast happened at a busy junction in the Midan district and state TV showed the shattered blood-stained windows of what appeared to be a bus carrying policemen.
The BBC's Lina Sinjab is in Damascus.