The council decided to send up to 500 additional peacekeepers to Ivory Coast for no longer than six months to reinforce the 8,500 blue helmets already deployed in the West African nation, the world's top cocoa producer.

"The members of the Security Council urge the Ivorian stakeholders to meet their commitments to organize the first round of elections on 31 October, as agreed by all parties," the 15-nation council said in a statement.

"They further stressed the need for the parties to ensure calm prior to, during and after the vote," it said.

Voting is scheduled for October 31, but six dates have already been missed in the past five years because of disputes over voters' identities and the disarmament of rebel groups.

Elections are needed to draw a line under Ivory Coast's civil war of 2002 and 2003, which caused investors to flee what had been West Africa's economic success story.

Voting could make way for reforms necessary to fix Ivory Coast's cocoa sector, which supplies two-thirds of world demand but has been hurt by under-investment.

U.N. special envoy to the Ivory Coast Young-Jin Choi told Reuters after the council meeting he was not worried about the possibility of violence in the run-up to the vote on October 31, a date he was optimistic the Ivorians can keep.

The situation was less certain in the event of a run-off election in November. Asked if there could be violence ahead of a run-off vote, Choi said: "I hope not."

President Laurent Gbagbo's signature on a decree this month validating definitive voter lists was hailed as a huge step considering he failed to approve earlier versions because he suspected they included names from Burkina Faso and Mali.

About 6.38 million people had registered to vote, but about 1 million of those were disputed, mostly on grounds of nationality.

The issue fueled the initial conflict, when many Ivorians from the north said they had been wrongly excluded from a presidential election in 2000.

The final voters list has 5,725,720 names on it.