The Central African Republic's main rebel grouping on Wednesday accused the president of not keeping his end of the peace deal that brought an end to their military offensive earlier this month.

The Seleka coalition, which had looked poised to advance on the capital Bangui before a power-sharing deal was struck under regional pressure on January 11, charged President Francois Bozize was clinging to the defence portfolio.

"President Bozize... has scrapped the defence minister job and opted for an assistant defence minister. In other words, he remains head of state and de facto defence minister," Seleka spokesman Florian Ndjadder told AFP.

The Libreville negotiations that yielded a deal between the regime and the rebels provided for a member of the opposition to be appointed prime minister and a Seleka member to be handed the defence portfolio.

Opposition leader Nicolas Tiangaye was subsequently named prime minister but the process appears to have snagged over the defence portfolio.

The Seleka coalition launched its offensive in early December, arguing that Bozize's regime had failed to comply with previous peace deals that should have given demobbed rebels jobs or integrated them in the regular forces.

Bozize's camp has in recent days also accused the rebels of violating the terms of the deal agreed in the Gabonese capital by pressing on with military operations and being responsible for several looting incidents.

Ndjadder also demanded the departure of South African troops deployed in the impoverished country to support Bozize when the rebels were gaining territory and threatening to topple the regime.

"South Africa is meddling in Central African affairs," he said, demanding "the unconditional departure of the South African forces... that came to Bozize's rescue."