An air strike late on Tuesday hit a detention centre for migrants in the Tajoura suburb of the Libyan capital of Tripoli.
There were casualties among the migrants, said an official who works in the department to combat illegal migration that runs the centre.
The U.N. refugee agency UNHCR said on Twitter that it was “extremely concerned about … accounts of refugees and migrants deceased”.
No more details were immediately available.
The nationalities of the affected migrants are not known yet.
According to the United Nations, more than 3,800 refugees and migrants remain in detention centres in Tripoli close to the areas where fighting is taking place.
Tajoura is home to several military camps of forces allied to Libya’s internationally recognized government which has been battling eastern forces trying to take Tripoli.
On Monday, the eastern-based Libyan National Army (LNA) said it would start heavy air strikes on targets in Tripoli after “traditional means” of war had been exhausted.
The LNA has failed to take Tripoli in three months of fighting and last week lost its main forward base in Gharyan which was taken back by Tripoli forces.
Libya is a main departure point for migrants from Africa and Arab countries trying to reach Italy by boat. Thousands are held in government-run detention centres.
Since early April, the Libyan National Army (LNA) has been engaged in an offensive to gain control over Tripoli.
The UN-backed Libyan Government of National Accord (GNA) has been waging a counteroffensive to prevent the LNA from capturing the city.
Libya fell into chaos after its long-time ruler, Muammar Gaddafi, was deposed and killed in 2011.
Thousands of people from across Africa embarked on a perilous journey across the Mediterranean in the hope of reaching Europe.
The European Union made a deal with Libya in 2017 to stop the exodus but the United Nations has warned that many migrants faced arbitrary detention and unlawful killings in the North African country.
Libya has been torn apart by the ongoing conflict. The eastern part of the country is governed by the parliament, backed by the LNA and located in Tobruk.
The GNA, headed by Prime Minister Fayez Sarraj, operates in the country’s west and is headquartered in Tripoli. – AFP.