France, Oct. 1 -- Kaka, a prominent figure in Nigerien journalism and a former RFI correspondent, has spent more than three decades reporting from the country.

He was previously imprisoned in Niamey from September 2007 to October 2008, accused of complicity in threatening state security or authority after interviewing leaders of the Tuareg-led Niger Movement for Justice (MNJ).

Press freedom group Reporters Without Borders (RSF) is calling for an investigation into his disappearance, saying it has strong reason to believe the country's military authorities are involved.

It has now referred the case to the United Nations Committee on Enforced Disappearances, having previously referred it to the African Union's special rapporteur on freed...