In a joint call for an investigation to bring those responsible to justice, UN migration agency, IOM, and UNHCR, the UN refugee agency, spoke of the “appalling toll” caused by Tuesday’s reported airstrike on the Tajoura Detention Centre in a suburb of the Libyan capital.

Secretary-General António Guterres, said in a statement that he was "outraged by reports that at least 44 migrants and refugees, including women and children, have been killed and more than 130 injured". He condemned "this horrendous incident in the strongest terms", and expressed his deepest condolences to the families of the victims, wishing the injured a speedy recovery.

“The airstrike that left scores dead, also left dozens injured,” IOM and UNHCR said, noting that they expected the final death toll to include many more victims.

“Such an attack deserves more than condemnation,” both agencies added, in an appeal for a probe “to determine how this happened and who was responsible, and to bring those individuals to account”.

According to one report, a cell was hit containing more than 120 people, some of the more than 600 men, women and children being held at the centre.

This is despite the fact that the coordinates of this detention facility “and the knowledge that it housed civilians had been communicated to the parties to the conflict”, the UN’s top human rights official, Michelle Bachelet, said, in reference to ongoing clashes between the UN-recognised Government and forces loyal to Khalifa Haftar.

“(This) indicates that this attack may, depending on the precise circumstances, amount to a war crime,” she insisted, before urging all parties to the conflict “to abide by their obligations under international humanitarian law, and to take all possible measures to protect civilians and civilian infrastructure, including schools, hospitals and detention facilities”.

Also noting the exact coordinates had been given, the UN chief called for an independent investigation, "to ensure that the perpetrators are brought to justice".

"The Secretary-General further reminds all parties of their obligations under international humanitarian law to take all feasible precautions to avoid, and in any event to minimize, incidental loss of civilian life, injury to civilians and damage to civilian objects, and to refrain from directing attacks against civilians", said the UN chief's statement. "This incident underscores the urgency to provide all refugees and migrants with safe shelter until their asylum claims can be processed or they can be safely repatriated."

Ghassan Salamé, head of the UN Support Mission in Libya (UNSMIL) and Special Representative of the Secretary-General, echoed the High Commissioner’s assessment of the attack, describing it as a “cowardly act”.

He added: "This attack clearly could constitute a war crime, as it killed by surprise innocent people whose dire conditions forced them to be in that shelter.”

He said that “the absurdity of this ongoing war today has led this bloody carnage to its most hideous and most tragic consequences”, calling on the international community to denounce the crime and pursue justice for the victims, mostly believed to be migrants - men, women and children - from other African nations, hoping to reach Europe. 

Around 3,300 migrants, refugees, remain arbitrarily detained

In addition to the detainees at Tajoura, some 3,300 migrants and refugees remain arbitrarily detained inside and around Tripoli, according to IOM and UNHCR.

They are held in “in conditions that can only be described as inhumane”, the agencies said, while highlighting the dangers posed by intensifying clashes nearby.

Echoing their call for these centres to be closed, UN High Commissioner Michelle Bachelet explained that UN staff have documented severe overcrowding, torture, ill-treatment, forced labour, rape and acute malnutrition in the troubled country’s facilities.

“I also repeat my call for the release of detained migrants and refugees as a matter of urgency, and for their access to humanitarian protection, collective shelters or other safe places, well away from areas that are likely to be affected by the hostilities,” she said.  

According to the World Health Organization (WHO), intensified airstrikes and heavy shelling in and around Tripoli have displaced at least 104,000 people.

For the past several months, the forces of the self-styled Libyan National Army, which holds sway in eastern and parts of the country, have laid siege to the outskirts of the Libyan capital, where the UN-recognized Government of National Accord under Prime Minister Fayez al-Sarraj is based. 

According to news reports, the forces loyal to LNA Commander Haftar, threatened new air strikes on Tripoli in recent days, after their advance stalled, although the LNA has reportedly denied responsibility for the direct airstrike on the centre. 

Military targets have included Mitiga airport – targeted with shelling four times since the latest escalation began, while field ambulance and field hospital teams continue to be hampered by “continuous shelling and armed clashes”.