Observers from the African Union and the Economic Comunity of West African States (ECOWAS) have said Guinea elections were conducted transparently, despite opposition claims of irregularities.

On Monday, opposition leader Cellou Diallo declared himself winner, saying his own tally gave him a first-round victory over president Alpha Conde.

Diallo’s claim was swiftly rejected by the electoral commission, which called it “premature” and “void”.

Addressing journalists in the capital, Conakry, Augustin Matata Ponyo, the AU’s head of mission in Guinea, said on Tuesday the ballot was held “in transparency”.

"The elections were held in a transparent, secure, calm and peaceful environment, once again demonstrating the maturity of the Guinean people and political actors", he asserted.

Tension is building in the country ahead of the release of official results. Diallo's supporters have held celebrations in the capital.

Francis Behanzin, ECOWAS' Peace and Security commissioner urged candidates "to resort to legal avenues" if they are aggrieved.