The United Nations and Ivory Coast are sending more troops to patrol the West African nation's border with Liberia after a deadly clash there killed at least 23 people.

Ivory Coast military spokesman Alla Kouakou told reporters Monday the death toll from the attack last week includes at least 19 civilians.

Officials and residents are blaming the attack on mercenaries allied with former President Laurent Gbagbo, who was ousted this year after months of violent turmoil following last year's election.

The crisis was sparked when Mr. Gbagbo refused to step down after losing an election to current President Alassane Ouattara. At least 3,000 people were killed during the four months of unrest.

Mr. Gbagbo was finally arrested in April of this year. Since his defeat, many of the mercenaries who fought for him have been staying in internment camps in Liberia, and security along the border has remained tenuous.