An attack which killed more than 44 migrants at a detention centre outside the Libyan capital could constitute a war crime, a UN official said.At least 130 people were injured in the attack, which the Libyan government blamed on an air strike by forces loyal to a warlord, General Khalifa Haftar.Gen Haftar's forces accuse the government side of shelling the centre.Most of the dead are believed to be sub-Saharan Africans who were attempting to reach Europe from Libya.Thousands of migrants are being held in government-run detention centres in Libya. The location of the centre attacked on Tuesday and the information that it housed civilians had been passed to all parties in Libya's conflict, the UN's High Commissioner for Human Rights, Michelle Bachelet, said."This attack may, depending on the precise circumstances, amount to a war crime," she said. It was the second time the shelter was hit, she added.UN Secretary-General António Guterres said he was "outraged" by the reports and called for an independent investigation "to ensure that the perpetrators are brought to justice".Separately, the UN Security Council has changed its agenda, and will discuss the situation in Libya behind closed doors later today.Libya has been torn by violence and division since long-time ruler Muammar Gaddafi was deposed and killed in 2011.

What do we know about the attack?

A hangar housing migrants at the Tajoura Detention Centre, which houses 600 migrants, reportedly took a direct hit.Women and children were among the victims, Guma El-Gamaty, a member of the UN-backed political dialogue group, told BBC World Service.An official in the Libyan health ministry, Doctor Khalid Bin Attia, described the carnage for the BBC after attending the scene:"People were everywhere, the camp was destroyed, people are crying here, there is psychological trauma, the lights cut off."We couldn't see the area very clear but just when the ambulance came, it was horrible, blood is everywhere, somebody's guts in pieces."The UN issued a stark warning in May that those living in the Tajoura centre should be moved immediately out of harm's way. "The risks are simply unacceptable at this point," the UN refugee agency said.