The move was expected to further escalate tensions between the opposition leaders who boycotted Saturday's presidential election and those loyal to the West African nation's incumbent leader of nearly a decade.
By the evening, the country's electoral commission had released provisional results from fewer than half of the country's 108 departments.
It was not immediately clear when a final tally would be announced, however the opposition continued to attack the legitimacy of the vote itself.
Pascal Affi N'Guessan, one of the top opposition candidates who later boycotted the vote, said late Monday that Henri Konan Bedie, the country's 86-year-old former president, would head up a council of transition.
A new transitional government then will be be formed and tasked with preparing "the framework for the organization of a fair, transparent and inclusive presidential election," he said.
"Opposition parties and political groups affirm that the call for civil disobedience is maintained and call on the Ivorian people to remain mobilized until the final victory," he said, reading from a statement.
It was not immediately clear how the opposition could proceed with their plan given that the country's electoral commissions are heavily weighted with Ouattara supporters as is the constitutional council that is to certify official results from Saturday's election.
Tensions surrounding the vote have raised fears of post-election violence in the West African country, where more than 3,000 people died in 2010-2011 when then-President Laurent Gbagbo refused to concede defeat to Ouattara.
The opposition says more than 30 people have died in violence related to Saturday's vote.
The opposition coalition has asserted that only 10% of Ivorians cast ballots, without citing its source. Election officials have yet to release a nationwide voter turnout rate, but international observers said Monday that "a significant portion of the population did not vote."
Ouattara initially promised not to seek a third term after nearly a decade in power, but changed his mind after his party's candidate to succeed him died from a heart problem in July.
The 78-year-old president, who is popular with international donors, has said he was motivated to run again because of his love for his country.
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