A Nigerian journalist has been released after he was arrested in neighboring Niger while reporting on the migration of Africans across the Sahara desert to Europe.

Lawan Adamu, the deputy editor of the privately-owned Nigerian newspaper Daily Trust, was arrested in the desert city of Agadez on Oct. 18, according to Premium Times, a privately-owned news source in Nigeria. On Oct. 19, at around 6 p.m., Adamu was released and handed over to Nigerian immigration official, according to the Daily Trust.

Adamu told the newspaper he was detained because Niger authorities did not want him to report on the issue because Nigeriens profit from the migration trade. Agadez is used as a transit route for West African migrants crossing the Sahara desert to get to Libya, then across the Mediterranean to Europe.

Mannir Dan Ali, executive director and editor-in-chief of Daily Trust, told the BBC’s Hausa language service that Adamu was arrested on arrival at Agadez even before he started his work. He was accused of not having the relevant documentation to work in the area. However, Adamu said he had received official permission for reporting in Agadez before he left Nigeria.

“At first they said they will hand me over to our ambassador in Niamey but I think because of pressure, they handed me over to our immigration officials at the border town,” Adamu said in an interview after his release.