Prosecutors said the head of the campaign’s leadership team in Niger was detained in connection with an army airstrike on suspected jihadists in the country’s south.
Abdoulaye Seydou, head of an activist group called M62, appeared before Niamey’s criminal court on Monday, prosecutor Shaibu Moussa said on television in the evening.
He was placed in pre-trial detention, Moussa said.
M62 and other civilian groups blamed the defense and security forces for massacres of civilians when they carried out helicopter raids on an illegal gold mine last October, on the grounds that the alleged killers of two policemen were hiding there.
The government admitted that the airstrikes were carried out after two policemen were killed in Tamou, near the border with Burkina Faso.
It says seven people were killed and 24 injured in the raids, but political opposition and civic groups say the death toll was much higher.
Moussa said that after the “terrorist” attack on the police station and the army’s retaliatory strike, “unidentified persons” went to the goldmine “to burn down stores and warehouses used as housing.”
Referring to the police investigation, Moussa said the arson was set up to create false evidence to blame the army and “support allegations of massacres.”
M62 senior spokesman Falmata Taya acknowledged that members of the movement went to Tamou two days after the air raids, but only “for on-the-spot fact-checking.”
Niger, the world’s poorest country according to the United Nations Human Development Index, is fighting jihadist insurgents in the country’s southwest and southeast.