Niamey - Police in Niger have detained three journalists from the Anfani private radio station as well as a union leader who criticised President Mahamadou Issfouou on air, the station's director-general told Reuters.
Niger police arrested Anfani's editor in chief Abdoul-Razak Idrissa, and two journalists, Haoua Maigari and Moussa Hassane on Wednesday.
"They are being held in detention and I think this is linked to an interview they conducted with a union leader from the education sector," Gremah Boukar, director-general of Anfani, told Reuters.
The union leader, Ismael Salifou, has also been detained.
Police sources, who asked not to be identified, said the union leader is accused of making insulting remarks about the president and inciting ethnic hatred during the interview broadcast on 22 January.
The journalists are being held as his accomplices, the police sources said.
Political tensions have risen in Niger since August, after a reshaping of Issoufou's ruling coalition that saw National Assembly leader Hama Amadou enter the opposition.
Since late January, six journalists, two politicians and a member of civil society have been briefly detained on charges including slander, inciting ethnic hatred and plotting against state security. They have all subsequently been released.
"Niger is witnessing a decline in freedom of the press. We will fight until our comrade Ismael Salifou is freed," Salou Yacouba, spokesperson for the national association of education workers, told journalists.
Niger decriminalised slander in June 2010.