Ivory Coast's President Alassane Ouattara has secured a fourth term in an election which two of his biggest challengers were barred from, provisional results show.

Ouattara, 83, won 89.8% of the vote, the electoral commission announced on Monday, with businessman Jeal-Louis Billon coming in a distant second with only 3.09%.

The landslide victory was anticipated following the disqualification of key opponents, including former President Laurent Gbagbo and ex-Credit Suisse CEO Tidjane Thiam, both of whom urged their supporters to boycott the election.

Voter turnout reached just 50.1%, according to the electoral commission.

Simone Gbagbo, the former president's ex-wife who was allowed to contest the election, received 2.42% of the vote.

Monday's results are provisional and the final outcome will be announced by the Constitutional Council, which will rule on any election petitions.

The opposition coalition comprising Gbagbo and Thiam's parties denounced the election as a 'civilian coup d'état,' stating they would not recognize Ouattara as a legitimately elected leader.

Ouattara has been in power since 2011, following Gbagbo's arrest after his refusal to accept defeat in the 2010 election. Originally limited to two terms, a 2016 constitutional amendment allowed Ouattara to seek re-election in 2020, a vote also boycotted by the opposition.