Angola's ruling party claimed victory Sunday in the oil-rich nation's chaotic landmark election despite opposition attempts to have the result cancelled.

The ruling MPLA of President Jose Eduardo Dos Santos, in power for more than 30 years, predicted a sweeping victory after polls closed late Saturday.

Voting in the first election since the end of a three decade long civil war was extended because of delays and a lack of election registers in many polling stations. An African observer mission said the vote had been credible but an EU mission delayed giving a verdict.

"We are going to win big time," Popular Movement for the Liberation of Angola (MPLA) spokesman Rui Falcao said. "The victory is not in question, only whether we get the numbers required."

Partial official results released by the electoral agency late Saturday indicated an early lead for the MPLA.

With 35 percent of votes counted from across the country, MPLA won by 81.7 percent followed by UNITA with 10.5 percent.

MPLA is winning in most provinces, including UNITA's former stronghold of central and southern provinces, including Huambo, Bie and Benguela.

The opposition UNITA is trailing the MPLA in 14 of 18 provinces.

The Union for the Total Independence of Angola (UNITA) -- the MPLA's main foe during the civil war which left 500,000 dead -- called on Angola's Constitutional court to annul the vote.

It said the delays and lack of ballot material had rendered the vote "illegal." UNITA has also accused the ruling party of misused state funds and monopolising the media during the campaign.

Alceides Sakala, head of UNITA's parliamentary group, told AFP: "As far as Luanda is concerned, it was a scandal, the way it was organised."

Despite the confusion Angolans turned out in force to vote for the first time since fighting ended in 2002. The electoral commission reported a high turnout but did not give a figure.

International observers gave cautious approval. Monitors from the 15-nation Southern African Development Community (SADC) group said the vote was "peaceful, free, transparent and credible" and reflected "the will of the people".

But it said delays and procedural glitches could have put off many voters.

The head of the European Union observer mission, who on Friday morning called the voting process a "disaster," was more circumspect.

"There have been problems and they're trying to change them," Luisa Morgantini said. "We'll see what will happen."

The EU mission said it would delay its official report on the elections until Monday.

The MPLA said it hoped to get the two thirds majority needed to change the constitution.

Dos Santos, in a rare public speech just ahead of the vote said he was ready to overhaul his government in the cause of greater unity, amend the constitution and work towards a more equitable distribution of the national wealth.

According to UNITA, the fact that the problems with polling stations mainly affected Luanda's sprawling shantytowns -- where 90 percent of the city's five to seven million residents live -- was a ploy to discourage voting in areas where the MPLA was not expected to get a majority.

Angola has a booming economy that stems from vast oil and diamond riches which has fuelled double-digit growth but over two-thirds of its people remain mired in poverty, living on less than two dollars a day.

The state media has spoken of a massive turn-out with millions of voters but no official figures have been given yet. About half of Angola's 17 million inhabitants had registered to vote.

Angola attempted to hold an election in 1992 -- but UNITA claimed it was fixed, withdrew from the second round and new hostilities started.