Regional observers endorsed Zimbabwe's elections as credible and fair on Sunday but long delays in issuing results stoked concerns that President Robert Mugabe was trying to cling to power by rigging the result.

The election is the most important since independence, with Zimbabwe's economic collapse and a two-pronged opposition attack facing Mugabe with his most formidable challenge.

Two dissenting South African members of the observer mission refused to sign a positive preliminary report by the Southern African Development Community (SADC) and said the results delay "underscores the fear that vote rigging is taking place."

They said there was evidence of "widespread and convincing" victories by the opposition MDC party, which also expressed concern about the delays.

The MDC earlier said it had won the election but Mugabe's government warned the opposition it would regard such claims as a coup attempt.

SADC mission chairman Jose Marcos Barrica of Angola told reporters through an interpreter the election "has been a peaceful and credible expression of the will of the people of Zimbabwe."

Mugabe, in power for 28 years, is being challenged by MDC leader Morgan Tsvangirai and ruling ZANU-PF party defector Simba Makoni, who both accuse the former guerrilla leader of wrecking a once prosperous economy and reducing the population to misery.

Although the odds seem stacked against Mugabe, 84, analysts believe his iron grip on the country and backing from the armed forces will enable him to declare victory. The MDC accused him of widespread vote-rigging.

"FREE AND FAIR"

Barrica expressed concern about the voters roll, opposition access to the media and statements by the heads of security forces who had said they would not accept an opposition victory.

But he added: "We saw that the basic conditions for a free and fair election were there."

The dissenting mission members from South Africa's opposition Democratic Alliance (DA), said in a statement it "is impossible for this deeply flawed electoral process to be viewed as a credible expression of the will of the people of Zimbabwe."

SADC, which critics say has been too soft on Mugabe, has unsuccessfully tried to mediate an end to Zimbabwe's crisis, which has turned a quarter of the population into refugees.

More than 24 hours after the polls closed in presidential, parliamentary and local elections, only a trickle of results had emerged.

Tendai Biti, secretary general of the main MDC opposition party, told diplomats and observers that early results showed it was victorious. "We have won this election," he said.

Projections from 12 percent of the vote showed MDC leader Tsvangirai winning 67 percent nationally, Biti said.

Results usually begin emerging soon after polls close.

Officials said the delay was caused by the complexity of counting in three different polls but Biti expressed concern.

"We're aware the results are final in most constituencies but they are deliberately taking their time to announce (them)...The whole idea of having an election is so you can have a result," he said.

"COUP D'ETAT"

Zimbabwe's security forces, which have thrown their backing firmly behind Mugabe, said before the election they would not allow a victory declaration before counting was complete.

Government spokesman George Charamba warned the opposition against such claims. "It is called a coup d'etat and we all know how coups are handled," he told the state-owned Sunday Mail.

Residents in the eastern opposition stronghold of Manicaland said riot police stopped a victory demonstration by about 200 MDC supporters on Sunday. There was no violence, they said.

The United States said it was worried by the conduct of the election and the absence of most international observers.

"The Mugabe regime is a disgrace to the people of Zimbabwe and a disgrace to southern Africa and to the continent of Africa as a whole," Secretary of State Condoleezza Rice told reporters during a visit to Jerusalem.

Zimbabwe is suffering from the world's highest inflation rate of more than 100,000 percent, chronic shortages of food and fuel, and an HIV/AIDS epidemic that has contributed to a steep decline in life expectancy.

Mugabe accuses the West of sabotaging Zimbabwe's economy. He rejected vote-rigging allegations.