The federal government is starting flights to evacuate thousands of Nigerians from Libya which will continue until all those wanting to return home have done so, foreign minister, Mr Geoffrey Onyeama, said on Saturday.

Nigerians have recently been the largest national group among African migrants travelling to Libya and trying to cross from there to Italy by sea.

Since local armed factions and Libya's coastguard began blocking more migrants from leaving in July last year, large numbers have been trapped in Libya, where they often face dire conditions and abuse, including forced labour.

International Organization for Migration (IOM) has in recent months accelerated a "voluntary returns" programme to repatriate migrants from a number of countries. Nigeria now joins Niger in organising bilateral returns.

"The main objective, and we're very focused on that objective, is to get these Nigerian citizens back home as quickly as possible," Onyema told reporters during a visit to Tripoli.

"Our president has made available all the resources necessary to repatriate all the Nigerians here.

"We have two planes arriving today and God willing we are hoping to evacuate anything up to 800 Nigerians today."

Nigeria had been expecting to fly back about 5,500 migrants, Onyema said, but the situation on the ground made the actual number hard to ascertain.

"Some of the difficulties with getting precise numbers is that some are within the control of the central government in camps, some are clearly outside the camps, some are also in less accessible areas where there might not be full central government control and authority," he said.

Facilitating voluntary returns could also be complicated by lack of access, Onyema said.

Criminals involved in smuggling and trafficking migrants "also (have) an interest that a number of them should not be repatriated, because these represent economic assets for them".

Libya has been in turmoil since a 2011 uprising, with rival governments and armed factions vying for power.

Onyema was hosted by the internationally recognised government in Tripoli, which has struggled to assert its authority on the ground.

Slightly fewer than half as many migrants reached Europe by sea in 2017 than 2016, the IOM said on Friday, largely due to a drop in numbers crossing from Libya.

Reuters