Ten defeated presidential candidates in the Central African Republic (CAR) are calling for the result of a December 27 election to be annulled and the vote repeated, citing irregularities and low turnout, according to a joint statement late on Tuesday.

On Monday, the electoral commission declared President Faustin-Archange Touadera the winner of the race, with voter turnout of over 76% despite an offensive by rebel groups seeking to derail the vote.

However, only half of the country's 1.8-million eligible voters were able to register for the vote due to the violence.

Ten of the 17 candidates are now rejecting this result, saying turnout of registered voters was just 37% and that the insecurity disrupted campaigning and the electoral process.

"We demand an annulment pure and simple and a rerun of the election," they said in the statement.

There was no immediate comment from the electoral commission or Touadera.

A disputed election could further destabilise the gold and diamond producer, whose population of 4.7-million has endured waves of militia violence since 2013 that has killed thousands and forced more than a million from their homes.

A powerful coalition of opposition politicians has also called for the vote to be repeated, including former president, Francois Bozize.

Touadera and the United Nations, which has over 12 800 uniformed peacekeepers in CAR, have accused Bozize of being behind the rebel offensive, which briefly seized the country's fourth-largest city ahead of the election.

Bozize has not been reachable for comment.

His party has previously denied the government's accusations, but some in the party have suggested they are working with the rebels.

Touadera came to office in 2016 after Bozize was overthrown in a rebellion three years earlier. He struggled to restore peace in his first term and swathes of the country remain beyond government control.