As fighting intensifies in Libya, tens of thousands of migrants remain at risk. The United Nations is calling for migrant detention centers to release their detainees. CGTN's Asta Tall reports.

African migrants hoping to cross to Europe use Libya as a final transit point. Many end up in detention centres, where poor conditions are common. 

UN officials now worry immigrants stuck in these detention centres could be forcefully recruited to fight.

RAVINA SHAMDASANI SPOKESPERSON, OFFICE OF THE UN HIGH COMMISSIONER FOR HUMAN RIGHTS "Based on previous experience in Libya, we are also concerned that migrants may be used as human shields or forcefully recruited to fight as well."

They are 5,700 refugees currently being held in Libyan detention centres. This doesn't account for those being held in informal centres.

BABAR BALOCH SPOKESPERSON, THE UN HIGH COMMISSIONER FOR HUMAN RIGHTS "We have spoken to refugees in detention centres who tell us that they can hear the clashes. And many are really scared. So, joining the call with others, we are concerned about the situation of refugees and migrants in detention, who are detained in the areas where active conflict is ongoing. We are asking, advocating for release of all refugees and migrants from detention."

The UN's refugee agency has relocated 150 refugees from a detention centre in southern Tripoli.

UNHCR is working with officials to safely relocate other vulnerable migrants. Asta Tall, CGTN.