President Michel Djotodia of the Central African Republic has dissolved the rebel group that helped bring him to power in a coup six months ago.
A statement by his office said anyone acting in the name of the rebel Seleka Coalition would be punished.
The rebels have been blamed for looting and many deaths after former President Francois Bozize was ousted in March.
Supporters of Mr Bozize have recently staged an offensive, leading to the death of nearly 100 earlier this week.
The UN has warned that CAR could become a failed state, threatening the region.
A statement issued by Mr Djotodia's office on Friday said: "The Seleka Coalition is dissolved over the length and breadth of the Central African Republic's territory. Only the Central African security force is in charge of protecting our territorial integrity.
"Any individual or group of individuals who acts in the name of Seleka after the publication of the present decree... will incur the full sanctions under the law."
Mr Djotodia, a former rebel leader, was sworn in as president earlier this month after his forces ousted Francois Bozize in March.
Aid workers have accused undisciplined former rebels of looting the healthcare system, as well as robbing civilians, since the Seleka coalition of armed groups took power in March.
CAR has huge deposits of minerals such as gold and diamond deposits but has been plagued by chronic instability since independence in 1960.
Mr Djotodia has promised to relinquish power after elections scheduled for 2016.
Mr Bozize is currently in France after initially fleeing to Cameroon when Seleka fighters seized the capital, Bangui.
Earlier this week, his force launched an offensive north-west of the city - the first large-scale operation the former president's forces have staged since he was forced from power.