The country was spared the kind of widespread violence that many feared would erupt during voting on Saturday, as President Alassane Ouattara seeks a third term that his opponents say is unconstitutional.

Opponents of 78-year-old Ouattara say he is breaking the law by running again because the constitution limits presidents to two terms, and risks shattering the fragile peace that has been in place since a civil war killed 3000 people in 2010-11.

The streets of the country's economic engine, Abidjan, were quiet on Sunday, as they had been on election day, as many stayed at home for fear of violence.

Some had already left the commercial capital for villages in the provinces ahead of the vote.

However, some areas did see violence, and the atmosphere remained tense ahead of partial results expected on Sunday.

"Young armed men from the surrounding villages ... fired on the other young people," said Germain N'Dri Koffi, mayor of the town of Tiebissou in the centre of the country, the heartland of opposition candidate, former president Henri Konan Bedie.

Four were killed and 27 injured by bullets and machetes, he said. One other person was killed in the pro-Bedie town of Niable, a government official said on condition of anonymity.

Opposition candidate Pascal Affi N'Guessan said on Sunday that 12 people had died, without providing details.

The towns affected are not major producers of cocoa, of which Ivory Coast is the world's top grower. However, some buyers told Reuters on Sunday that middlemen were avoiding trips into rural areas of cocoa-growing regions for fear of violence.

Ouattara says he can run again under a new constitution approved in 2016, and is doing so only because his handpicked successor died unexpectedly in July.

Bedie and Affi had urged supporters to boycott the vote. That is expected to hand Ouattara victory, but may undermine the legitimacy of a third term.

Australian Associated Press