An influential ex-rebel leader told Ivory Coast's army to mutiny on Wednesday and back a rival breakaway government in the wake of a contested presidential election that the opposition says was illegal.

President Alassane Ouattara won the election with 94% of the vote, according to the electoral commission.

However, the opposition has boycotted the vote, arguing Ouattara's bid for a third term broke a legal two-term limit and undermined the country's democratic process.

Police in riot gear surrounded the houses of two of Ouattara's main rivals on Wednesday after the government accused them of sedition for creating a parallel administration in defiance of Saturday's victory declaration.

The standoff has raised concerns about instability in the world's top cocoa producer, where a civil war killed 3,000 people in 2010-11 following a disputed election between Ouattara and his predecessor, Laurent Gbagbo.

This election season, over 40 people have died in clashes.

Guillaume Soro, who led the rebels that swept Ouattara to power during that war, but whose relationship with the president has since soured, released a message on Facebook on Wednesday night calling on the army to join the opposition government.

"Turning now to our security and Defence forces … I'm asking you to disobey illegal orders and join the national transitional council," he said. "We cannot, out of fear, allow dictatorship in Ivory Coast by Alassane Ouattara."

It was unclear if there was any reaction to the statement late on Wednesday, but it added to tensions that many fear could help destabilise a region beset by political unrest.

In neighbouring Guinea, a similar election crisis in which President Alpha Conde won a third term last month caused rioting in which dozens have died.

Guinea also has a two-term limit but like Ouattara, Conde said a recent change to the constitution allowed him to restart his mandate.