More than 400 West Africans have been rescued in the desert in northern Niger, the International Organization for Migration (IOM) has said, Reuters news agency reports.
Search and rescue teams found the migrants, split in two groups, at the desert border town of Assamaka on Monday and Tuesday, the IOM added.
The one group was made of 347 people who had arrived in Assamaka on foot on Monday. The group was made up of nationals from 13 countries, including Mali, Guinea and Senegal.
It added that most of them had been taken to a transit camp where they could receive food, water and medical assistance. A further 92 were rescued on Tuesday. Reuters quoted the IOM as saying.
The IOM has reported a sharp rise in the number of migrants left to walk across the border between Algeria and Niger through the desert this year.
Niger is a transit point for thousands of migrants on their way to Libya or Algeria, from where they try to cross the Mediterranean to reach Europe.
In 2015, Niger introduced a law making people-smuggling punishable by a jail term of up to 30 years.
The army also stepped up patrols in the desert.
In July, European Parliament President Antonio Tajani said the flow of migrants through Niger fell by 95 percent between 2016 and 2017