A Syrian activist group says a suicide car bomber has killed more than 50 Syrian soldiers and pro-government gunmen.

The Britain-based Syrian Observatory for Human Rights says the attack in the village of Ziyara in the central province of Hama was carried out by Jabhat al-Nusra, an al-Qaida-inspired Islamic militant group.

The death toll could not be independently verified.

State-run news agency SANA said the blast occurred outside a state-run development agency. It said Monday’s blast caused deaths but gave no figure.

The Observatory also reported that an air raid on the northern town of Harem killed at least 20 rebels. It said a rebel commander was seriously wounded in the raid.

At least 137 people were killed in Syria on Monday, according to the Local Coordination Committees of Syria. Israel Radio reported at least 190 killed in clashes between rebels and government forces.