South Africa’s President Jacob Zuma has congratulated Zimbabwean leader Robert Mugabe on his re-election, in sharp contrast to Western governments which questioned the credibility of a rushed, disputed vote.

African monitors broadly approved the conduct of the election but Mugabe’s main rival, Movement for Democratic Change (MDC) leader Morgan Tsvangirai, has said he will challenge the results in court with evidence of massive vote-rigging, irregularities and intimidation.

The sharply divergent views of Wednesday’s vote surfaced after Zimbabwe’s election officials declared a landslide win for Mugabe and his ZANU-PF party, giving Africa’s oldest president five more years at the helm of a nation he has ruled for 33.

The standoff raises some fears the southern African nation risks repeating the turmoil that followed another contested vote in 2008.

Election violence then forced Zimbabwe’s neighbours to broker a shaky unity government between ZANU-PF and the MDC.

But Sunday’s ‘‘profound congratulations’’ extended to Mugabe by Zuma, leader of Africa’s economic powerhouse, reflected a willingness by the continent’s diplomatic bodies to swallow the re-election of Mugabe, 89, for the sake of regional stability.

Mugabe, one of the grand old men of southern Africa’s liberation fight that ended white minority rule, is admired as a defiant nationalist by some Africans, though others share the West’s view of him as a ruthless despot who wrecked Zimbabwe.

‘‘President Zuma urges all political parties in Zimbabwe to accept the outcome of the elections, as election observers reported it to be an expression of the will of the people,’’ the South African leader said in his statement.

Zimbabwe’s capital Harare was calm on Sunday, with many residents going to church. Newspaper billboards proclaimed ‘‘ZANU-PF gloats over victory‘‘, ‘‘Mugabe romps to victory’’ and ‘‘Tsvangirai disputes election results’’.

Western observers were barred from Wednesday’s elections.

Monitors from the African Union and the Southern African Development Community (SADC) who observed them made a point of stressing that they were peaceful, in contrast to the violence of 2008 polls, and also endorsed them as broadly free.

In contrast, the United States and European governments, which have sanctions in place against Mugabe over past election-rigging, listed a litany of alleged flaws in the vote, from lack of availability of the voters’ roll to pro-Mugabe bias in the media and security services that skewed the election run-up.

In Zimbabwe, independent domestic monitors had described the election as ‘‘seriously compromised’’ by registration problems that may have disenfranchised up to a million people.

Anti-corruption watchdog Global Witness, citing links between mining companies, ZANU-PF insiders and Zimbabwe’s pro-Mugabe military, has also alleged that state diamond revenues may have been spent on securing the Mugabe re-election.

ZANU-PF has angrily rejected all vote-rigging allegations.

US Secretary of State John Kerry spelled out Washington’s distrust of the result in no uncertain terms.‘‘Make no mistake: in light of substantial electoral irregularities reported by domestic and regional observers, the United States does not believe that the results announced ... represent a credible expression of the will of the Zimbabwean people,’’ he said in a strongly worded statement on Saturday.

Former colonial power Britain expressed ‘‘grave concerns’’. Foreign Secretary William Hague said the reported irregularities ‘‘call into serious question the credibility of the election’’.

The 28-nation European Union has also pointed to ‘‘identified weaknesses in the electoral process and a lack of transparency,’’ completing a picture of general Western scepticism.