Libyan officials allowed at least 100 migrants to walk free on Tuesday from a detention centre in the capital Tripoli that was hit by a deadly attack last week.

The July 3 airstrike, killed 53 people and injured 130 others, the World Health Organization (WHO) said in its latest death toll on Twitter.

It occurred as eastern forces Libyan National Army (LNA) under General Khalifa Haftar keep up a ground and aerial offensive to wrestle control of Tripoli from the U.N.-backed government.

Officials at the centre, run by the U.N.-backed government in an eastern suburb of Tripoli, said they took the decision after the migrants protested over not being included in an evacuation list by the United Nations’ refugee agency (UNHCR).

A resident from Tajoura, a suburb in eastern Tripoli, said migrants were seen marching from the detention centre.

It was not immediately clear where they intended to go.

Following their departure, about 110 other migrants remain at the centre, lying in the open air and using mattresses for shelter from the sun, the official said.

“They don’t want to go back inside the hangar as they’re afraid of any further air strikes,” the official added.

Libya has been beset by violence since the 2011 ouster and killing of former leader Muammar Gaddafi. 

Gaddafi's removal created a void that various armed groups sought to fill, including human trafficking cells. 

The North African country then became a preferred departure point for migrants seeking to reach Europe illegally. Tight anti-trafficking measures by Europe led to the creation of migrant holding centers in Libya and other migrant departure points. Thousands of migrants remain in various holding centers across Libya, even as the UN calls for their return to their countries of origin.