A relative says Niger's agriculture minister has been arrested over his alleged involvement in a baby-trafficking scandal that has shaken the country's political class.

Issa Ali said Abdou Labo was transferred Saturday to a prison in the town of Say, 70 kilometers south of the capital, Niamey. He was arrested Friday.

Labo's wife had already been arrested along with 16 other people over their suspected links to the network involving babies from neighboring Nigeria. The suspects have been scattered in prisons across the country.

A wife of National Assembly President Hama Amadou was also arrested, and there have been calls to lift his parliamentary immunity so he can be questioned.

Amadou is a political rival to President Mahamadou Issoufou, and his allies have decried the arrests as politically motivated.