The electoral commission said it had finished counting ballots after the polls closed at nightfall but would not make the result public until until today.
Incumbent President Laurent Gbagbo faces Alassane Ouattara, a former prime minister and senior IMF official, in a tight race that has triggered conflict and rekindled simmering tension in the world’s biggest cocoa grower.
Five members of the security forces were killed in the west of the country, shortly before vote counting got under way, according to Pascal Affi N’Guessan, Gbagbo’s campaign manager.
Two security sources said the killings took place outside three different polling stations where angry Ivorians complained of being blocked from voting.
Ivory Coast has been divided since a 2002-2003 civil war left rebels in charge of the north, and unrest has wreaked havoc on what had been a West African economic success.
The election is meant to heal that divide, and the first round took place in a good-natured atmosphere on Oct. 31.
But that has given way to a heated contest in the run-off between the top two candidates. At least seven other people have been killed in the run-up to the vote.
Election observers held late evening talks with U.N. mission chief Y.J. Choi after reports of irregularities emerged.
“We have some concerns,” the head of the E.U. mission, Cristian Dan Preda, told Reuters by telephone. He said there were reports of “roadblocks, tensions in the polling booths, a lack of materials” which were not reported in the first round.
As counting began, groups of the rivals’ supporters gathered outside many polling stations along the wide boulevards of the lagoon-side city of Abidjan.