Zimbabwean electoral officials say the first results from Friday's presidential runoff poll are expected to emerge Saturday.
Vote counting continued through the night, as the United States and Britain again denounced the election as a sham and moved to bring new pressure on the government of President Robert Mugabe.
British Prime Minister Gordon Brown said the run-off was a "new low" for Zimbabwe and said the world is "uniting" in rejecting what he called Mr. Mugabe's illegitimate regime.
U.S. Secretary of State Condoleezza Rice said the United States is drafting a U.N. resolution meant to send a "strong message of deterrence" to Zimbabwean officials. The resolution could be introduced in the U.N. Security Council as early as Monday.
Late on Friday, the Security Council said conditions for a free and fair vote did not exist in Zimbabwe, but stopped short of calling the runoff illegitimate as some members wanted.
Mr. Mugabe is virtually assured of victory because he was the lone candidate following the withdrawal of opposition leader Morgan Tsvangirai earlier this week. Mr. Tsvangirai says violence against his supporters made the election impossible.
Zimbabwe's state-run Herald newspaper says there was "massive turnout" on Friday, although officials have not released any numbers. Witnesses say turnout was generally low, following a call for a boycott from Mr. Tsvangirai.
Observers say that in some areas, ruling party militia forced people to vote by threatening them with bodily harm.
Despite the U.S. and British calls for more pressure on Mr. Mugabe, African foreign ministers meeting in Egypt say they oppose more sanctions against his government. The ministers say dialogue between Mr. Mugabe and the opposition is more likely to resolve the crisis.
The United States, Britain, and European Union have an array of travel and financial sanctions against President Mugabe and more than 100 of his associations for alleged human rights violations.
Mr. Mugabe has ruled Zimbabwe since the country won independence from Britain in 1980. He lost the first round presidential election to Tsvangirai on March 29. However, official results showed Tsvangirai falling just short of the majority needed to avoid a runoff.
Some information for this report was provided by AFP, AP and Reuters.