Niger opposition presidential candidate Hama Amadou was taken into custody on Saturday, as he returned back to his country after a year in exile.
"He was arrested on leaving the plane. Police presented him with a warrant issued for his arrest," said lawmaker Amadou Salah.
Hama, who is an ally of President Amadouadou Issoufou had vowed to return to run in the presidential election in February.
Last year, he left the country over allegations of newborn baby trafficking.
Government had said that it would detain Amadou, if he came back to the country.
A security source said "The gendarmerie proceeded on Saturday to arrest Hama Amadou in an execution of an arrest warrant against him.”
Several supporters who rushed into the airport to welcome him after getting information of his arrival were also arrested
"There have been at least a dozen supporters of Hama who were arrested, including members of this political party bureau," said a security source.
Security forces set up roadblocks at the airport and many shops closed.
Police used tear gas to scatter dozens of Hama supporters and they reacted by throwing stones.
On the other hand, Niamey Governor Hamidou Garba stated that while a motorcyclist was trying to get past a road block, he hit a child and caused his death.