The highest court in Mozambique, the Constitutional Council, confirmed the disputed October election results that extended the Frelimo party's 50-year grip on power.
Daniel Chapo, Frelimo's presidential candidate, secured 65 percent of the vote, the seven-judge bench ruled, revising down the initial results of nearly 71 percent, announced in November by the National Electoral Commission (CNE).
Venancio Mondlane, the Podemos candidate, remained in second place with 24.19 percent of the votes (compared to around 20 percent according to the CNE results).
Ossufo Momade of Renamo obtained 6.62 percent of the votes, and Lutero Simango of the MDM secured 4 percent of the ballots.
The Constitutional Council dismissed Podemos' request for a recount of the votes. It also rejected Renamo's and the MDM's requests for new elections.
Mondlane has repeated that the 9 October vote was stolen from him. And several international observer missions have also said there were irregularities.
Mounting tension
Tension started mounting in the capital Maputo ahead of the court decision with many businesses shut.
The main roads into the city centre were barricaded by police and access to the presidential palace and Constitutional Council office shut, the French news agency AFP reported.
Tensions grow in Mozambique as police fire tear gas at protesters
The final results follow two months of street protests that left more than 100 people dead.
Mondlane has taken refuge abroad for fear of his safety. He has vowed to call a popular uprising if the Constitutional Council were to approve Chapo's victory.
"Difficult days will come," the 50-year-old said, after appeals to disenchanted younger voters.
Chapo, 47, will take over from President Filipe Nysui, whose second term ends on 15 January.
He will be Mozambique's first president born after independence and the first not to have served as a Frelimo fighter.
The former provincial governor has been criticised for his limited experience in politics or in Frelimo governments which have ruled the country since independence from Portugal in 1975.
Some observers fear the Constitutional Council's ruling is likely to spark further protests in the country.
Amnesty International reported that the government has repeatedly cut internet access across the country and blocked social media sites for nearly a week.
At least 130 people have already been killed in clashes with police since October, according to the civil society monitoring group Plataforma Decide since October’s election.
Meanwhile, the country's disaster management agency said that Cyclone Chido killed at least 120 people in Mozambique during its sweep through the Indian Ocean last week.
Cyclone Chido leaves dozens dead and devastates Mozambique
(with newswires)