Harare, Zimbabwe (CNN) -- South African President Jacob Zuma congratulated Zimbabwe's Robert Mugabe on his re-election, urging opposition groups Sunday to accept the results of "the successful harmonised elections."
Zuma's stance appears to be at odds with the United States, the United Kingdom and Australia, all of whom have called into question Wednesday's presidential and primary polls.
Zimbabwe's election commission said 89-year-old Mugabe won 61% of the vote, besting Prime Minister Morgan Tsvangirai's 34%, to lead the nation for another five years. Mugabe has been the only leader an independent Zimbabwe has ever known.
Tsvangirai, 61, called the balloting "a fraudulent and a stolen election" -- and said he plans to mount a court challenge.
Will of the people?
In his statement Sunday, Zuma said all parties should accept the election's results because "election observers reported it to be an expression of the will of the people."
Election observers and foreign officials raised doubts Saturday about the way the election was conducted, though some of them noted it was peaceful -- in contrast to the last election, in 2008, where post-vote violence left at last 200 people dead and thousands injured.
U.S. Secretary of State John Kerry, in a statement Saturday, criticized "the culmination of a deeply flawed process."
"In light of substantial irregularities reported by domestic and regional observers, the United States does not believe the results announced today represent a credible expression of the will of the Zimbabwean people," Kerry said.
British Foreign Secretary William Hague, meanwhile, commended the peaceful nature of the vote, but expressed concern over how it was conducted.
The reported irregularities "call into serious question the credibility of the election," Hague said.
On Sunday, Australian Foreign Minister Bob Carr called for a do-over.
"These appear to have disenfranchised large numbers of voters and raised doubts about the credibility of the election results," he said in a statement.
"Given our doubts about the results, Australia calls for a re-run of the elections based on a verified and agreed voters roll."
With his controversial win, Mugabe is set to see his time in power extended to 38 years.
Tsvangirai ran unsuccessfully against Mugabe in 2002 and was later arrested several times, jailed on charges of treason and severely beaten in police custody.
He faced off against Mugabe in the last election and won more votes than the president, though not enough to avoid a runoff.
Violence broke out, and Tsvangirai then pulled out of the runoff claiming widespread voter intimidation and the torture, mutilation and murder of his supporters.
Months later, after international pressure and successful negotiations, Mugabe and Tsvangirai signed an agreement giving Tsvangirai the post of prime minister in a Mugabe-led government. It has been an uneasy coalition ever since, one that included a brief boycott of the coalition by the MDC over the arrest of a party leader.
Journalist Columbus S. Mavhunga reported this story from Harare, and Faith Karimi reported and wrote from London.