Full provisional results of elections in the Democratic Republic of Congo will be announced Sunday, the electoral commission said on Friday, with a large victory expected for incumbent President Felix Tshisekedi.

Some 44 million people were registered to vote on December 20 in chaotic elections to choose a president, national and regional lawmakers and municipal councillors.

Out of the 15.9 million votes counted by Friday evening, Tshisekedi was well ahead with about 73 percent of the votes in the central African nation.

The election was hit by bureaucratic disarray, as the electoral commission struggled to get voting materials to polling booths on time in the huge and fragile country -- roughly the size of continental western Europe -- leaving some people unable to cast ballots.

Voting was officially extended by a day, but continued for much longer in some remote areas.

The head of the electoral commission, Denis Kadima, told journalists on Friday that the full provisional results will be announced on December 31.

Results had originally been expected then, but the date had not been confirmed by the commission since the vote was held. The final results will be confirmed in January by the Constitutional Court.

The opposition has claimed there was "total chaos" during the vote, and denounced irregularities in the polling.

The archbishop of Kinshasa likewise described the election as a "gigantic organised mess".

An election-observation mission run by the Catholic Church and Protestant churches also highlighted "numerous cases of irregularities" and raised questions about the legality of the shambolic voting process.