The Observatory said the blast had been close to a state security office. State news channel Syria TV said the “terrorist” explosion had been between two residential buildings in the al-Suleimaniya district of Aleppo, behind a post office building.
The opposition reported heavy raids by security forces and fighting with the opposition in northern and southern Syrian provinces and suburbs of Damascus.
In the capital, as crowds gathered for memorials to victims of Saturday’s car bombs, security forces broke up an opposition march of more than 200 people when protesters began shouting “the people want to topple the regime.”
The phrase has echoed through the wave of Arab uprisings that began last year and has toppled autocratic rulers in Tunisia, Egypt, Libya and Yemen. “They were walking through an area in central Damascus, near SANA [the state news agency]. At first they shouted slogans against violence and the police didn’t do anything, but as soon as they started to call for regime change the police rushed in and started beating people with canes,” said Rami Abdelrahman, from the Syrian Observatory for Human Rights.
The protest, which called for non-violent resistance to the government, had been led by moderate opposition leaders previously tolerated by the government because of their calls for dialogue and rejection of foreign intervention. Activists said the Sunday march aimed to commemorate the peaceful roots of Syria’s uprising, which has been overshadowed by a growing armed insurgency against state security forces.
Security forces arrested Mohammed Sayyed Rassas, a leader of the National Coordinating Body for Democratic Change (NCB), an opposition group which had visited China and Russia in attempts to promote dialogue between Assad and the opposition.
Most opposition groups have rejected the NCB over its insistence on non-violence and its stance against foreign intervention, arguing the government’s fierce crackdown has made arming the uprising inevitable.
Police also briefly arrested Fayyez Sara, who headed the Committee to Revive Civil Society, other activists said.
Syrian government forces have crushed an opposition stronghold in the central city of Homs and have been pounding opposition strongholds in northern Idlib.