Opposition leader Morgan Tsvangirai accused President Robert Mugabe of forcing Zimbabweans to vote on Friday in an election in which the 84-year-old leader is the only candidate.
Mugabe, in power for 28 years, went ahead with the vote despite a wave of international condemnation after Tsvangirai withdrew because of state-backed violence against his supporters.
Tsvangirai, who has taken refuge in the Dutch embassy for the last six days, told a news conference millions of people were staying away from the polls despite intimidation. He returned to the embassy after speaking.
"What is happening today is not an election. It is an exercise in mass intimidation with people all over the country being forced to vote," Tsvangirai said.
The opposition says almost 90 of its supporters were killed.
Turnout was low in urban areas where Tsvangirai's Movement for Democratic Change is traditionally strong. But it was not clear how many voters went to the polls in rural districts.
Tsvangirai, calling the poll a farce, earlier urged people to abstain but said they should vote if they were in danger.
"Whatever might happen, the results.will not be recognised by the world. No matter what you are forced to do, we know what is in your heart. Don't risk your life. The people's victory may be delayed but it won't be denied," he said in a statement.
Voting began shortly after 6 a.m. British time and turnout was much lower in urban areas than in parliamentary and presidential elections in March, when people queued from the early hours. Polling was due to end at 6 p.m. British time.
Tsvangirai won the March 29 poll but fell short of the majority needed for outright victory.
DREAM
The G8 group of rich nations lambasted Zimbabwe for going ahead with the run-off and the United States said the U.N. Security Council may consider fresh sanctions next week.
Tsvangirai said he understood South African President Thabo Mbeki planned to recognise Mugabe's re-election. But he said it would be a "dream" to expect his MDC to join a national unity government with Mugabe's ZANU-PF.
Mbeki, the designated regional mediator in Zimbabwe, has been widely criticised for a soft approach towards Mugabe despite an economic crisis that has flooded South Africa and other countries with millions of refugees.
Tsvangirai said voters were being ordered to record the serial numbers of their ballot papers to identify how they cast their ballots. Pro-Mugabe militias had threatened to kill anybody abstaining or voting for the opposition, he said.
Voters had their little finger dyed with purple ink.
"There is no doubt turnout will be very low," said Marwick Khumalo, head of monitors from the Pan African Parliament.
