Central African Republic (CAR) President Faustin-Archange Touadéra has won a third term after securing an outright majority in last month's presidential election, provisional results show.

The 68-year-old mathematics professor was widely expected to win after the main opposition coalition boycotted the poll, citing concerns about electoral fairness.

Touadéra campaigned on his security record in the chronically unstable nation after rebels seized power in 2013, a crisis that led the government to enlist support from Russian mercenaries and Rwandan soldiers.

He has faced heavy criticism after a 2023 constitution removed term limits, allowing him to keep running for office.

More than 2.4 million people registered for the 28 December general election, which observers described as largely peaceful despite delays caused by the late arrival of voting material and problems with the electoral register.

Touadéra secured 76% of the vote, according to preliminary results announced late on Monday by the election agency.

His closest challengers, Anicet-Georges Dologuélé and Henri-Marie Dondra, both former prime ministers, received 15% and 3% of the vote respectively.

Both have called for the results to be annulled, alleging widespread irregularities and fraud.

On Friday, Dologuélé said there had been "a methodical attempt to manipulate" the outcome.

The main opposition coalition, known by its French acronym BRDC, boycotted the election, saying it was unlikely to be fair.

The government has denied the claims.

The Constitutional Court has until 20 January to rule on any challenges and declare the final results.

The CAR is one of Africa's poorest and most unstable countries, even though it is rich in resources such as diamonds and uranium. The UN estimates that about half the population is dependent on humanitarian aid.

Since 2013, the landlocked country has been mired in conflict after rebels seized power, ousting then-President François Bozizé.

A 2019 peace deal between the government and 14 armed groups helped ease tensions, though six of the groups later withdrew from the agreement.

Analysts say Touadéra's win could bolster the interests of Russia, which has provided security assistance in exchange for access to resources such as gold and diamonds.

The CAR was one of the first African countries where Wagner, a Russian mercenary group, became active, providing security to Touadéra.