TRIPOLI, Aug. 6 (Xinhua) -- An airstrike killed more than 40 people and injured more than 50 others in the southern Libyan city of Murzuq later Sunday, a local official said Monday.

"A building in central Murzuq where hundreds of people gathered for reconciliation meeting between rival parties in the city was suddenly attacked yesterday, killing more than 40 people and injuring more than 50 others," Mohamed Omar, council member of the Murzuq municipality, told Xinhua.

Omar confirmed that those killed were all civilians and said no military positions in the city were targeted by the airstrike.

The UN-backed government condemned the attack, calling the UN Support Mission in Libya and the international community to "assume their responsibility and investigate the crimes committed by the militias in Murzuq."

The eastern-based rebel army, which has been controlling Murzuq since February, announced the launching of airstrikes on Chadian militants around the Murzuq city but denied targeting civilians.

The rebel army has been leading a military campaign since early April to take over Tripoli from the government.

The conflict has so far killed more than 1,000 people, injured more than 5,700 others, and displaced more than 120,000 people, according to the World Health Organization.

Libya has been mired in conflicts and chaos ever since the fall of former leader Muammar Gaddafi in 2011.