If confirmed, the results mean another term for President dos Santos, 70, who has ruled since 1979. Final results are expected to be announced on Monday.

The state-ruin newspaper Jornal de Angola has already declared Mr Dos Santos the victor, saying on its front page on Sunday: "The MPLA is the big winner of the general elections of 2012... Jose Eduardo dos Santos is president-elect."

Angola's seaside capital was calm and there were no signs of any celebration or uproar in the streets, which indicated the overwhelming MPLA victory in only the third election since independence from Portugal in 1975 was widely anticipated.
Silver-haired Dos Santos is Africa's second longest serving leader after Equatorial Guinea's President Teodoro Obiang Nguema Mbasogo.

The provisional results gave the MPLA's closest challenger, former rebel group UNITA, nearly 18 percent, while the third-placed CASA-CE party was approaching five percent in its first election test after being formed by UNITA dissident Abel Chivukuvuku four months ago.

Chivukuvuku told reporters his party, which along with UNITA had complained repeatedly of serious irregularities in the vote preparations and the electoral process, was analysing the results before deciding whether to accept or reject them.

But another prominent CASA-CE member, candidate for Luanda William Tonet, dismissed the provisional results as "cheating taken to its maximum level".

"This is like a declaration of war by the MPLA ... it indicates to citizens that there can be no alternative through the electoral route," he told Reuters.

Sources at UNITA said party president Isaias Samakuva would challenge the announced results.

Friday's vote passed smoothly and without any serious incidents, according to officials and election observers.

As they cast their ballots, many citizens called however for better power, water, health and education services and a more equal share-out of the country's oil wealth.

It was the second election since the end a decade ago of a 27-year civil war in which Dos Santos' MPLA emerged victorious over UNITA. The MPLA then crushed its rival politically by obtaining 82 percent of the vote in the last 2008 elections.

An oil boom fuelled rapid growth averaging 15 percent a year between 2002 and 2008 and prospects for national economic growth remain buoyant, but distribution of this wealth among Angola's 18 million people has been very unequal.

Thrusting new buildings and construction cranes punctuate the bayside skyline of the seaside capital Luanda, but sprawling poor slums known as "musseques" fringe the overcrowded city.

Dos Santos had campaigned on a platform portraying him as a guarantor of peace combined with a pledge to spread the country's riches more evenly and widely among the population. 

Meanwhile, African Union observers have given national elections in Angola a clean bill of health, despite opposition claims of fraud and illegality.

The AU team said the poll had been "free, fair, transparent and credible".

Ahead of Friday's vote, the main opposition party Unita had called for a delay, expressing concern about a lack of transparency.

The vote was the second since the civil war ended a decade ago.