HARARE, Zimbabwe (CNN) -- President Robert Mugabe was sworn in Sunday after the Zimbabwe Electoral Commission declared he overwhelmingly won the country's disputed runoff election.

"I, Robert Gabriel Mugabe, do swear that I will well and truly serve Zimbabwe in the office of president, so help me God," Mugabe said at the State House complex in Harare, standing before a red-robed judge wearing a white wig.

His words were met with loud applause.

The international community has roundly called the election -- allegedly marred by violence and vote rigging -- a "sham."

Many voters expressed fear of government retaliation if they did not take part in the vote to extend Mugabe's rule. Some said they were required to report the serial numbers on their ballots to Mugabe's Zimbabwe African National Union -- Patriotic Front. Watch as Mugabe gets sworn in »

Zimbabwe's Electoral Commission released the final results of Friday's runoff vote, showing that Mugabe won by an almost 9-to-1 margin, with voter turnout about 42 percent.

The final tally, according to the electoral commission, showed Mugabe snaring 2.2 million votes, or about 86 percent of the ballots, to opposition candidate Morgan Tsvangirai's 233,000.

The commission's quick turnaround was a contrast to the five weeks it took the ZEC to release results from the March 29 election.

Tsvangirai's Movement for Democratic Change quickly denounced the results, calling the election "a one-man race, a one-man circus."

"We have nothing to do with the so-called Mugabe win," MDC spokesman Nelson Chamisa "In effect we believe that whatever ZANU-PF and Mugabe are doing is just but a continuation of the sham."

He added, "We do not in any way associate ourselves with the so-called win."

A government official confirmed earlier Sunday that invitations had been sent out for Mugabe's inauguration, but said the ceremony would not be held until official results were announced and a winner declared.

A Zimbabwean journalist said there was activity at the presidential residence Saturday night. Tents were erected and trucks drove in and out of the property, leading reporters to speculate that a swearing-in ceremony was in the works.

Tsvangirai was among those invited to the ceremony, but he would not attend, Chamisa said before the ceremony.

"How do you invite a man to a false wedding?" he asked.

Mugabe was the sole candidate in the runoff. Tsvangirai pulled out last week, citing violence and intimidation, but the government said it was too late to remove his name from the ballots.

Before the results were official, Mugabe said he won in all parts of the capital city of Harare and many parts elsewhere. Though there were reports Friday of low voter turnout, the state-run newspaper lauded record turnout, and Mugabe said he did not know what prompted people to vote in such overwhelming numbers.

Mugabe made the claims Sunday at a funeral for his wife's relative. It was broadcast on state television.

"Turnout was very low," Irene Petras, executive director of Zimbabwe Lawyers for Human Rights, said Sunday. "A lot of people [were] dragged to the polling station to fill out a ballot paper."

The MDC reported that ZANU-PF supporters herded rural voters to the polls and forced them to vote. The party said about 90 of its supporters have been killed in the weeks preceding the election.

Zimbabwean Deputy Minister of Information Bright Matonga said he would not "dignify the charges with comment" and declared the voting process peaceful. He also said MDC supporters burned down some polling stations.

Members of the Pan-African Parliament observer mission, however, said the election was not "free, fair and credible."

"The environment was tense, hostile and volatile," said Marwick Khumalo, a lawmaker from Swaziland. "And there was a high level of intimidation, violence, displacement of people, abduction and loss of lives."

The mission said opposition parties were not allowed to hold rallies and were shut out from broadcasting their campaign messages on state-run media.

"There was hate speech, incitement of violence and war rhetoric that instilled fear and trepidation amongst voters," Khumalo said.

Kenyan Prime Minister Raila Odinga called on the African Union to send troops to Zimbabwe, saying the ongoing crisis in the country is a "shame and embarrassment."

Odinga, a former opposition leader who became Kenya's prime minister after a power-sharing deal following a disputed election in that country, made the comments during a visit to his home province.

He made a similar appeal earlier this month.

"The information that we have right now is that Mugabe is proceeding with impunity, completely disregarding the world opinion," he said. "And I have suggested that the United Nations should support the African Union and come up with a peacekeeping force that will be deployed in Zimbabwe so that some calmer decisions can be facilitated."

Opposition leaders and international observers have called the election a "sham" -- a word that President Bush also used to denounce the voting.

Tsvangirai supporters say he defeated Zimbabwe's longtime leader in the March elections. But when the results were reported, the Mugabe-appointed commission said Tsvangirai had not won by enough to avoid a runoff.

Mugabe has been the country's only leader since it gained its independence from Britain in 1980.

Tsvangirai remained holed up for a sixth day Saturday at the Dutch Embassy in Harare, Chamisa said. Tsvangirai fled to the embassy last week, saying he feared for his safety.

Matonga on Saturday said that the government would be willing to sit down with Tsvangirai and MDC members "as long as they are not pushing the British agenda or an American agenda." Mugabe has called the MDC a creation of the West.

However, Tendai Biti, MDC secretary-general, said Saturday that the runoff had closed some doors in the eyes of the MDC.

"A government of national unity, as far as we're concerned, is history," he said, saying that some sort of transitional arrangement might be possible.

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