Migrants paying to get detained in Libyan centres

Despite the risks of rape, slavery or worse, many believe that their chances of making it to Europe are increased once inside the notorious centres.

The agency says others have also told them that they feel more secure inside the detention centres given the spiralling conflict in Tripoli, where darker-skinned Africans appear especially targeted.

"The darker your skin is, the less you speak Arabic, the more likely you could be abducted," Cochetel said of those outside the centres, noting around one million Libyans have fled to Tunisia.

Cochetel said those paying to get detained are being encouraged by traffickers and others in the false hope they will quickly be identified by the UNHCR and then sent off to Europe or elsewhere.

Their hopes are quickly dashed once they realise that registration with the agency does not mean resettlement.

Libya's UN-backed government of national accord does not officially recognise refugees. It also has a policy of arbitrarily locking up migrants.

Around 4,500 people are currently spread around some 19 detention centres in Libya. Of those, some 2,500 are asylum seekers under UNHCR's watch.

Cochetel said efforts are now underway to dispel the notion that being detained equates to resettlements.

Of all its resettlements from Libya, the agency takes around 80 percent from people inside detention centres and the remainder from outside.

"We would like to balance it very quickly to 50/50, so people don't think it is better to go to detention centres," he said.

Some are first sent to Niger or Rwanda before leaving for Europe or elsewhere. But the agency said it is also being squeezed by the lack of pledges from EU states when it comes to getting people out of the country.

Although Libya has a rough estimate of 46,000 refugee and asylum seekers, only around 2,400 pledges for resettlement have so far been made for 2020.

Of those, Italy is the only EU state to have come forward with 130 spots directly from Libya.

Some 15,000 people have so far this year attempted to leave the Libyan coast by boat to Europe. Over half have been intercepted by a Libyan coast guard that is part financed by the European Union and Italy.

Around one-third of those attempts were made by people from Sudan, followed by Bangladeshi and other nationalities.

The spike of Sudanese nationals may be linked to the insufficient aid and broader lack of hope among the some 390,000 found in refugee camps in Chad.

"Many young people they don't see any prospect for living in those camps for another decade. Many prefer to go to Libya to look for a job even if they know they could run into trouble," said Cochetel.