United Nations Secretary General Ban Ki-moon says he's gravely alarmed at reports from Syria that the government is continuing to shell populated areas.
He says UN ceasefire monitors have reported that the Syrian government is in contravention of the peace plan it agreed to, which has been endorsed unanimously by the Security Council. Under this plan, Damascus was to withdraw troops and heavy weapons from cities.
Mr Ban demanded that Damascus comply without delay.
government forces are accused of killing up to 70 people in a building in the city of Hama on Wednesday.
State television says the building was a terrorist bomb factory.
Pictures of injured children in hospital were shown on television.
The BBC reports the reports cannot be independently verified owing to government restrictions on foreign media.