The election in Zimbabwe this week was "seriously compromised" with up to 1 million people prevented from voting, the largest observer group has said.
Most of those turned away were in urban areas, where support for Prime Minister Morgan Tsvangirai is strong, according to the Zimbabwe Election Support Network.
It noted that fewer voters were rejected in rural areas, seen as strongholds of President Robert Mugabe, the BBC reports.
Mr Tsvangirai later described Wednesday's poll as a "huge farce". His comments came as Mr Mugabe's allies were already claiming a victory.
"We've buried the MDC [Mr Tsvangirai's Movement for Democratic Change]," a senior party source told Reuters. It is illegal to publish unofficial results.
Vote counting started overnight on Wednesday and the Zimbabwe Electoral Commission five days to declare who won the poll.
Police have warned they would take action against anyone trying to leak early results. Extra units - some in riot gear - have now been deployed in the capital Harare.
African regional observers have praised the peaceful nature of the election.