Election observers from southern African countries have criticised the conduct of the poll in Zimbabwe where votes are being counted.
The regional body called SADC said the voting was peaceful, but that some aspects fell short of local laws and its own guidelines.
Late on Wednesday more than 40 poll monitors were arrested as they were trying to compile their own vote count to compare with the official tally.
The arrests have been condemned by rights groups.
President Emmerson Mnangagwa is seeking re-election amid high unemployment and soaring inflation.
His main challenger is Nelson Chamisa of the opposition Citizens Coalition for Change.
BBC/Jide Johnson.
