Observers for a southern African regional bloc declared Mozambique's national elections free and fair Friday, after the main opposition Renamo party rejected provisional results.

The Southern African Development Community (SADC) said Wednesday's presidential and legislative elections "were generally peaceful, transparent, free and fair and credible".

The ruling Frelimo party earlier said it would rely on observers to validate the elections in the face of Renamo crying foul over partial results which put Frelimo ahead.

Early tallies and projections showed Frelimo's candidate Filipe Nyusi headed for victory with around 60 percent of the vote while Renamo's Afonso Dhlakama was struggling to win 30 percent of the ballots.

Renamo said the vote had been seriously flawed and claimed that Dhlakama had won outright, raising the spectre of post-election violence.

SADC -- which is made up of 15 member governments -- has previously been criticised for overlooking irregularities in polls from Zimbabwe to Malawi.

"Both national and international observers were there and watched the process. They will be able to say whether what Renamo says is true or not," Frelimo's spokesman, Damiao Jose told AFP.

"In Frelimo's opinion these elections took place in a calm, orderly, and transparent way. A few incidents... do not put into question the normal functioning of the process," Jose said. "It went very, very well."

Renamo pointed to "serious irregularities", including people voting more than once, ballot stuffing and polls opening late or not at all.

The Electoral Commission, which has admitted several "incidents" had occurred, was yet to hear from Renamo before it gives a formal reaction.

The commission's spokesman Paulo Cuinica, however believes that despite the incidents, the polls had been "free and fair".

"We are waiting for a statement or complaint from Renamo which we haven't received so far," Cuinica told AFP. So "no reaction until we have a formal complaint."

The SADC observers chief, South African foreign minister, Maite Nkoana-Mashabane, urged disaffected parties to resort to the available legal channels to lodge their protest.

Without naming any party, she reminded the Mozambican political players to abide by the pledges they made in the peace deal signed last month to end a two-year insurgency.

"We are still very convinced that whatever steps that any other political party would want to take, will still be guided by that commitment to peace and tranquillity in this country," she said.

The former rebel movement, which waged a 16-year war until signing a peace deal in 1992, ended a recently renewed low-level insurgency in the centre of the country just weeks ahead of the election.

Part of the deal to end the latest conflict involved disarming Renamo fighters. But that process was due to kick off only after the elections, raising fears of fresh violence.

The former guerrillas have claimed that all past elections have been stolen by Frelimo, which has been in power since independence from Portugal in 1975.

Any unrest could be disastrous for a country looking forward to the benefits of a mineral resources windfall as gas deposits are exploited.

"Investors are watching Mozambique closely and want stability and predictability," said Chatham House researcher Alex Vines, describing the election as the "most important" since the first post-war vote in 1994.

Foreign observer missions were Friday revealing their findings on the vote.

SADC said pre-election concerns raised by opposition such as reported violence in some provinces as well as alleged media and police bias in favour of the ruling party, could not have affected the outcome of the vote.

"Despite concerns raised, the (SADC) observation is that these concerns were not of such nature as to affect the overall credibility of the electoral process," said the group which deployed 145 observers across the vast southern African country.

The vote took place against a backdrop of rising discontent, with rapid economic growth in the southern African nation failing to benefit the bulk of a population that is among the world's poorest.

Incumbent President Armando Guebuza, from Frelimo, is prohibited by the constitution from running for a third term.