Taban and Ana Namiriano, the editor of the Juba Monitor newspaper, were summoned to the headquarters of the security services in Juba on 16 July. Namiriano was allowed to leave after questioning but Taban (who founded the Juba Monitor in 2000, when it was called the Khartoum Monitor) was detained without any formal charge being brought against him.

His state of health is worrying and it is not known where he is being held.

“We urge the South Sudanese authorities to free Alfred Taban without delay and to ensure that his rights are respected and that he has access to a doctor,” RSF said. “This leading journalist’s arrest constitutes yet another violation of media freedom in a country that has endured extensive violations of civil liberties since the start of the civil war.”

Several sources said the arrest of Taban, who also heads the Association for the Development of Media in South Soudan (ADMISS), was a reprisal for his 15 July “Let us speak out” column about a recent communiqué by the Inter-Governmental Authority on Development (IGAD), a regional group that is mediating in the South Sudanese conflict.

The IGAD statement took a firm tone with the leaders of both sides, President Salva Kiirr and Vice-President Riek Machar, calling on them to take their responsibility to end the violence that erupted on 7 July.

Since the start of this latest violence, in which hundreds of people have been killed and thousands displaced, officials have intensified repressive measures and the security services have imposed curbs on free movement. They had already been targeting journalists and human rights defenders in particular since the start of the year and many journalists are now in hiding.

John Gatluak Manguet Nhial, a respected journalist who coordinated and reported for Radio Naath FM in Leer, was killed with complete impunity in Juba’s Terrain Hotel on 11 July, probably because he is a member of the Nuer ethnic group.

South Sudan is ranked 140th out of 180 countries inRSF’s 2016 World Press Freedom Index, having fallen 26 places since the start of the conflict.