The agency said that reliable sources and refugees had reported criminals using vests and other items with logos similar to that of UNHCR at disembarkation points and smuggling hubs.
UNHCR said officials were present at official disembarkation points in Libya, providing medical and humanitarian assistance, such as food, water and clothes to refugees and migrants.
The refugee agency said it was opposed to the detention of refugees and migrants, but had officials monitoring the situation at Libyan detention centres, aiding and identifying the most vulnerable.
However, the agency insisted that they did not engage in the transfer of refugees from disembarkation points to detention centres.
The reports of criminals impersonating UNHCR staff came as the situation for refugees and migrants detained or living in the Libyan capital, Tripoli, had dramatically deteriorated.
The UN agency noted the violent clashes in Tripoli that erupted on Aug. 26, when tanks and heavy artillery were deployed in residential neighbourhoods.
The UN Support Mission in Libya (UNSMIL) said it had received reports of atrocities committed against refugees and migrants in Tripoli, including rape, kidnapping and torture.
Head of the mission, Ghassan Salamé, said that 61 Libyans were killed, and nearly 160 were injured, adding looting and crime are widespread, and described the city as being “on the brink of all-out war”.
UNSMIL brokered a ceasefire between the major parties to the conflict, halting the fighting and restoring some order after thousands had escaped the detention centres close to the clashes in a desperate attempt to save their lives.
UNHCR called for alternatives to detention to be put in place, including the immediate use of the Gathering and Departure Facility in Tripoli, which would serve as a platform to find safety in third countries, and which would be managed by the Libyan Ministry of Interior and by UNHCR.
The facility has the capacity to host 1,000 vulnerable refugees and asylum-seekers and is ready for use, the UN refugee agency said.
Edited by: Muhammad Suleiman Tola