The six people freed were close associates of Domingos Simoes Pereira, head of the PAIGC party that led the country to independence in 1974. Pereira has been in custody since the coup.

The releases are a "sign of good faith and a compromise for the return to constitutional normality and respect for international rights", the High Military Command, the junta's governing body, said in a statement seen by AFP.

The army seized power on November 26 after ousting outgoing president Umaro Sissoco Embalo in the wake of a presidential vote.

The military then suspended the electoral process and announced it was taking control of the west African country for a period of one year.

Another opposition candidate, Fernando Dias, took refuge in Nigeria's embassy, which granted him asylum, while Embalo fled the country after being briefly detained by the military at the time of the coup.

On Sunday, Senegal's foreign minister led a delegation to Guinea-Bissau, where he met with detained opponents and requested their release.

West African regional bloc ECOWAS this month threatened "targeted sanctions" on anyone obstructing Guinea-Bissau's return to civilian rule following the coup.

Before November's coup, Guinea-Bissau had already undergone four military takeovers and a litany of attempted insurrections since gaining independence from Portugal in 1974.