Four massive explosions ripped through a government-controlled section of Syria's largest city, Aleppo, killing at least 40 people and wounding nearly 100 others.

The Syrian government and its opponents said Wednesday three of the blasts were car bombs that targeted Saadallah Jabri Square, near a hotel that residents said housed pro-government militiamen.

An officers' club and other military and government buildings are also in the area. A fourth explosion detonated close to the nearby Chamber of Commerce.

The Britain-based Syrian Observatory for Human Rights, which has a network of observers inside Syria, said most of the dead were from the security forces.

Aleppo has seen increased fighting recently between the government and rebels opposed to President Bashar al-Assad. In recent days, large areas of the city's ancient covered market were burned as fighting spread to previously stable districts.

A pro-government television station broadcast video it said was the aftermath of the blasts. The images show extensive damage to several buildings with piles of rubble lying the street.

State media blamed “terrorists” for the bombings.

Rebels fighting to overthrow Mr. Assad last week announced a new offensive in Aleppo, Syria's commercial hub, but neither side has appeared to make significant gains so far.

The city is now split in two with Assad's forces mainly in the west and rebels in the east.

Meanwhile, the joint United Nations-Arab League envoy to Syria Lakhdar Brahimi is set to return to the region next week as he tries to revive efforts to end the 18-month conflict.

U.N. Deputy Secretary-General Jan Eliasson said Tuesday that Brahimi will be based in Cairo. He also said the U.N. wants to see a reduction in violence from Mr. Assad's government, followed by similar efforts by the opposition.