The International Organization for Migration (IOM) says it has airlifted 332 migrants from Niger out of the Libyan capital, Tripoli.
The migrants were stranded during the Libyan conflict that ousted Moammar Gadhafi. IOM officials say they are the first group of African migrants to be evacuated from Tripoli by air instead of by road or sea.
The group arrived in Niamey, the capital of Niger, earlier this week. Most of an estimated 2,000 Niger nationals still stranded in Tripoli also are seeking assistance to return home.
IOM spokesman Jumbe Omari Jumbe says his agency is planning further air evacuations for stranded African migrants from Chad, Gambia, Ghana, Mali, Nigeria, and Senegal.
"IOM is planning to speed up evacuations because of protection fears for stranded migrants who are exposed to arbitrary detention and harassment, and also because of the onset of cold temperatures at the moment," he said. "Most migrants live in damp and squalid conditions with no access to water, electricity and medicine, so there is a growing concern of health risks during this onset of the cold spell."
Jumbe says IOM is working with Libyan authorities to accelerate voluntary repatriation of thousands of migrants stranded in Tripoli and in Sabha to the south.
Migrant documentation is a particular challenge in Libya, he says, where few African countries have embassies, making it difficult to verify citizenship of an African national and issue temporary travel papers.
Jumbe says he does not know how many African migrants still remain in post-Gadhafi Libya.
Before the crisis, he says about one-half million African migrants were working in the country. Predominantly casual laborers - unskilled, semi-skilled and tradesmen - he says they were mostly young men in their 20s and 30s with no family members.
According to IOM, more than 90,000 Nigeriens so far have returned home from Libya. Officials say the organization and its partners have evacuated more than 314,000 migrants from Libya by land, sea and air, and that operations are set to continue for several more months.