HARARE (REUTERS) - Zimbabwe President Robert Mugabe's party claimed a landslide election victory on Thursday that would secure another five years in power for Africa's oldest head of state, but its main rival said the vote was invalidated by "monumental fraud".
Wednesday's voting was peaceful across the southern African nation, but the conflicting claims heralded an acrimonious dispute over the outcome that increases the chances of a repeat of the violence that followed a contested vote in 2008.
Releasing unofficial results early in Zimbabwe is illegal, and police have said they will arrest anybody who makes premature claims.
Election authorities are due to announce the official outcome by Aug. 5.
But a senior source in 89-year-old Mugabe's ZANU-PF party, who asked not to be named, said the result was already clear.
"We've taken this election. We've buried the MDC. We never had any doubt that we were going to win," the source told Reuters by phone.
Responding to the claim, a high-ranking source in Prime Minister Morgan Tsvangirai's Movement for Democratic Change (MDC) party described the election as "a monumental fraud".
"Zimbabweans have been taken for a ride by ZANU-PF and Mugabe. We do not accept it," the source, who asked not to be identified, told Reuters.
The MDC was to hold an emergency meeting later on Thursday.
As riot police took up position outside the MDC headquarters in central Harare, an independent election monitor, who also could not be named for fear of arrest, said early results were looking like a "disaster" for Mr Tsvangirai.
Western observers were barred, but the head of an African Union monitoring mission said on Wednesday the polls had initially appeared "peaceful, orderly and free and fair" - an assessment at odds with the view of the MDC and independent agencies.
The Zimbabwe Election Support Network (ZESN), the leading domestic monitoring body, said the credibility of the vote was seriously compromised by large numbers of people being turned away from polling stations in MDC strongholds.
It also cast doubt on the authenticity of the voters' roll, noting that 99.97 per cent of voters in the countryside - Mr Mugabe's main source of support - were registered, against just 67.9 per cent in the mostly pro-Tsvangirai urban areas.
In all, 6.4 million people, nearly half the population, had been registered to vote.
"It is not sufficient for elections to be peaceful for elections to be credible," ZESN chairman Solomon Zwana told a news conference.
"They must offer all citizens... an equal opportunity to vote."
Several political sources told Reuters that top MDC members had lost their parliamentary seats, including some in the capital, Mr Tsvangirai's main support base since he burst onto the political scene in the former British colony 15 years ago.
Party insiders spoke of their shock at the result.
If confirmed, Mr Mugabe's victory is likely to mean five more years of troubled relations with the West, where the former liberation fighter is regarded as a ruthless despot responsible for serious human rights abuses and wrecking the economy.
More than a week before the election, the United States, which has sanctions in place against Mr Mugabe, expressed concerns about the credibility of the vote, citing persistent pro-ZANU-PF bias in the state media and partisan security forces.
The view from Brussels, London and Washington is key to the future of Zimbabwe's economy, which is still struggling with the aftermath of a decade-long slump and hyperinflation that ended in 2009 when the worthless Zimbabwe dollar was scrapped.
An easing of sanctions against Mr Mugabe and his inner circle would allow Harare to normalise its relations with the International Monetary Fund and World Bank and access the huge investment needed to rebuild its dilapidated economy.
It would also spark a rush to exploit rich reserves of minerals such as chrome, coal, platinum and gold.