Libya has deported more than 500 African immigrants, state news agency Lana said, sending them to Niger as it tries to tackle an influx of refugees and Islamist militants.
Western powers fear Libya has become a safe haven for al-Qaida fighters as its government struggles to rein in militias and former rebels who helped topple Muammar Gaddafi two years ago.
Weak border controls and a small army lacking training and equipment have turned Libya into a weapons smuggling route for al-Qaida in sub-Saharan countries and a transit route for Islamist fighters heading to Syria's civil war.
People traffickers also use the remote desert borders with Egypt, Sudan, Niger and Chad to smuggle refugees into Libya from where many try to reach Europe by boat.
Authorities deported 350 illegal immigrants from Niger and 208 from Chad via its remote al-Tum crossing to Niger, Lana reported late on Tuesday, citing a security official.
In total 4,875 illegal immigrants of various nationalities were being held in detention centers, the agency said.
Hundreds of illegal migrants have died in the past two months on their way from North Africa to Italy. Many set off in small boats from the Libyan coast which authorities struggle to monitor.