The opposition suggests that delays are a sign that results from polling stations, especially in remote areas, are being massaged as they are collated centrally.
About 5.9m voters were registered in about 9, 000 polling stations, some in remote or sparsely-populated areas that were hard for the opposition or monitors to visit.
Election experts say it is unlikely the ballots will be able to reach the remote interior of a country where some 60, 000 polling stations are spread out over a territory the size of Western Europe.