Mozambique's ruling party, Frelimo, has won the country's divisive, violence-marred election, extending its 49-year grip on power in the southern African nation, according to official results.

Daniel Chapo, Frelimo's relatively unknown presidential candidate, seen as an agent of change, will replace Filipe Nyusi, who has served two terms.

At 47, Chapo, who gained 71% of the vote, will be the first president born after independence in 1975. His closest challenger, Venâncio Mondlane got 20%.

Chapo said in his victory speech: "We remained silent all this time, for respecting the law. We are an organised party that prepares its victories."

Following the announcement of the result, there have been violent protests in several towns and a number of people have been killed. There is also heavy police presence in some areas.

The election has been marred by allegations of rigging and the killing of opposition supporters, prompting protests across the country.

Zimbabwe's President Emmerson Mnangagwa, who has also been hit by allegations of election fraud over the years, prematurely congratulated Chapo on his "resounding victory", even before the results were announced.

Ossufo Momade, the candidate of former rebel group Renamo, which was previously the main opposition party, came in third with 6%.

Political analyst Tomás Vieira Mário told the BBC that Renamo had lost its “historical position” because Momade, 68, had failed to attract young voters.

The numbers announced surprised all voters, including some members and sympathisers of the ruling party, especially Frelimo's landslide victory.

The deputy chairperson of the electoral commission Fernando Mazanga, who was appointed by Renamo, said the “results are against electoral justice".

"These results do not represent the reality," he said.

The electoral commission says 43% of the more than 17 million registered voters took part in the poll.

Parliamentary and provincial elections were held at the same time as the presidential vote.

Frelimo won 195 of the 250 seats in parliament. The opposition Podemos, which backed Mondlane for president, got 31 seats and Renamo secured 20 seats.

Frelimo also won all the provincial elections.

President Filipe Nyusi followed the election results with a jubilant television address to the nation.

"With more than 70% of the votes, I don’t see any teacher failing a student," he said.

The election had been seen as a turning-point for the resource-rich country which is wracked by economic problems, corruption, and poverty.

Mondlane had called for a national strike on Thursday in protest at the alleged rigging.

He said that the protests would honour his lawyer and a party official who were shot dead last week in what he described as politically motivated killings.

He claimed that he won the election despite preliminary polls showing that Chapo was well ahead.

Mondlane now has until December to contest the results.

On Monday, he organised nationwide demonstrations, which were dispersed by police firing live rounds and tear gas.

The election has also been criticised by European Union (EU) election observers, who said some results may have been doctored.

They said there were "irregularities during counting and unjustified alteration of election results".

Political analyst Adriano Nuvunga decried what he called a pattern of fraudulent elections in Mozambique.

The electoral commission has declined to comment on allegations of vote-rigging, according to the Reuters news agency.

Chapo will be sworn into office in January.

Additional reporting by the BBC's Shingai Nyoka.