The British daily The Guardian said some 40 people were killed and at least 90 wounded in the blasts that caused extensive damage in Saadallah al-Jabri Square near a military officers' club and a hotel. The newspaper said another bombing occurred at the nearby Bab al-Jinein junction.
Citing the Syrian Observatory for Human Rights in Britain, the paper said most of the dead and wounded were soldiers from an officers club and a security branch.
The BBC said five bombs exploded in the city, some of them car bombs. The pro-government al-Ikhbariya television station broadcast pictures of bodies being pulled from buildings damaged by the explosions and showed a large crater in the road, BBC said. The network said some of the buildings were demolished in the explosions and the facades of others were ripped off by the blasts.
The BBC quoted state television as saying three terrorists dressed in military fatigues and wearing bomb vests were shot and killed before they could carry out attacks.
Earlier, the Syrian state news agency SANA said "three terrorist bombings" occurred in the city, causing "casualties and great material damage."
Syrian regime forces are preparing an offensive in Damascus and Aleppo Thursday to try to regain control, Albawaba.com reported. The site quoted the Syrian daily al-Watan as saying military reinforcements have been dispatched to Aleppo ahead of the offensive. There were also unconfirmed reports Syrian President Bashar Assad visited Aleppo to oversee preparations, the site said.