A grouping of former Seleka rebels in Central African Republic have expelled several members of their coalition who took part in the country's new government, saying they had not not been consulted on the appointments.
The decision on Sunday casts doubt on the future of the new cabinet and could prove a major setback for efforts aimed at ending violence that has killed thousands of people, forced a million to flee their homes and split the country in two.
"The ex-Seleka coalition neither supported nor put forward the names of the prime minister or ministers," the group's vice-president Nouredine Adam wrote in a statement.
"As a result, all members of the ex-Seleka coalition having participated in the present government are definitively excluded."
The government's formation has also sparked criticism among other political groupings.
The Movement for the Liberation of the Central African People - the party of former prime minister Martin Ziguele - announced on Sunday that it too was expelling its member serving in the government.
On Monday, witnesses said several hundred of the mainly Muslim Seleka rebels had left the capital of CAR and were now heading back to the country's north about eight months after they were forced from power.
The former French colony has been gripped by violence since Michel Djotodia led Seleka and some fighters from neighbouring Chad and Sudan, in an assault on the capital Bangui and seized power in March 2013.
Seleka's rule was marked by abuses that prompted a backlash from 'anti-Balaka' Christian fighters.
Cycles of tit-for-tat violence continued despite Djotodia's resignation from the presidency in January.
Most Muslims have fled the south of the country, creating a de facto partition. Some members of the Seleka leadership have pushed for this to be formalised.
Interim President Catherine Samba-Panza this month named Mahamat Kamoun, a Muslim and former head of cabinet to Djotodia, as prime minister.
He named three Seleka members to his 30-member cabinet, but the armed group rejected the government's composition, saying it had not been consulted.
About 2,000 French and 6,000 Africa Union peacekeepers have been deployed in the country but they have struggled to help Samba-Panza's weak transitional government stamp its authority on the mineral-rich nation.
A 12,000-strong UN peacekeeping force is due to start deploying in September.