Central African Republic's northern Seleka rebels said on Monday they would not take part in a national unity government as they were not consulted about the choice of prime minister and said they may rethink last month's ceasefire deal.
Interim President Catherine Samba Panza named Mahamat Kamoun on Sunday as the country's first Muslim prime minister.
He is tasked with forming a consensus government and guiding Central African Republic to elections next year in a bid to end sectarian violence that has killed thousands of people and displaced around 1 million.
Samba Panza took office in January when Seleka leader Michel Djotodia resigned amid an international outcry over abuses by the mostly Muslim rebels after they seized power in March 2013 in the majority Christian country. Christian 'anti-balaka' militia took up arms against them.
Kamoun, an economist, was the cabinet chief for Djotodia during his presidency but the rebels say he is not a member of Seleka. Kamoun has served as an adviser to Samba Panza since Djotodia's resignation.
"The transitional head of state did not think to open talks with Seleka and just decided to name a prime minister," General Mohamed Mousa Dhaffane, Seleka's second vice-president, said in a statement.
"Seleka has decided to not participate in the next government," Dhaffane said, adding the rebels could also rethink a ceasefire deal agreed last month in the capital of neighboring Congo Republic.