A court in Bangui provisionally released on Wednesday one of the Central African Republic's (CAR) main opposition leaders and adjourned his defamation hearing until next week.

International human rights groups regularly condemn the crackdown on all opposition forces in CAR, ranked by the United Nations as one of the four least developed in the world.

Crepin Mboli Goumba, a lawyer and coordinator for the leading opposition forum BRDC against President Faustin Archange Touadera, was brought before the high court after three days in detention, facing charges of defamation and contempt of court.

After his lawyers sought to have the case dismissed, presiding judge Matthieu Nana Bibi told the hearing the defendant "is released provisionally on condition he does not leave Bangui".

"I prepared myself mentally for everything that might happen in his trial, while condemning the breakdown in Central African justice," Mboli Goumba told the court.

He left the room to cheers and shouts of "freed, freed" from a handful of supporters to go to sign his release papers.

Mboli Goumba, who leads the PATRIE party and also has US nationality, was arrested Sunday on board a flight about to depart for Cameroon from Bangui airport.

The prosecutor's office announced he had been detained over comments made during a February 20 press conference, when he accused some magistrates of corruption.

He repeated the charge in a radio interview the following day saying "justice is no longer served in the name of the people".

Opposition gatherings are nearly always banned in CAR where NGOs denounce threats and intimidation against non-government politicians.

Opposition MP Dominique Yandocka has been in detention since December 15, despite his parliamentary immunity, accused of an attempted coup. Details of the accusation have never been made public.

New York-based Human Rights Watch last year said Touadera's regime "is repressing civil society, media and opposition political parties".

HRW urged the regime "to guarantee the independence of the justice system".