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, the election commission has announced.

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

At 47 years old, Chapo, who gained 71% of the vote, will be the first president born after Mozambique's independence in 1975. His closest challenger, Venancio Mondlane got 20%.

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

Zimbabwe's President 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.

Former rebel group Renamo, which was previously the main opposition party, came in third.

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

Parliamentary and provincial elections were held simultaneously.

The atmosphere in Mozambique's capital, Maputo, is tense, local media report. Footage shows empty streets and closed businesses.

The main opposition candidate, Mondlane, has called for a national strike on Thursday in protest at the alleged rigging.

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

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

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

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