Witnesses in Douentza say members of the group calling itself the Movement for Unity and Jihad in West Africa entered the town early Saturday morning and disarmed a local militia.
An Islamist leader told the Associated Press that the group was holding the militia members in custody.
Douentza is about 180 kilometers from the city of Mopti, which is the unofficial border between the Islamic-held north and the government-controlled south.
Islamists took over much of northern Mali in April after rebel soldiers overthrew the democratically-elected government.
Mali is also struggling with a long-running drought and famine, which has affected more than 4 million people. VoA.