By Ange Aboa
ABIDJAN (Reuters) - The United Nations and regional governments are deploying additional soldiers to Ivory Coast's border area with Liberia after deadly attacks on villages in the densely forested West African region, a military official said.
Some 23 people were killed in the latest raid by suspected mercenaries from Liberia last week in Ivory Coast's southwest, an area with a history of conflict between indigenous tribes and migrant farmers inflamed by a recent civil war.
"We have sent reinforcements to the area and (the United Nations mission in Ivory Coast) UNOCI has also added patrols to put an end to these attacks," Ivorian army captain Alla Kouakou told Reuters by telephone late on Saturday.
He said the governments of Guinea, Liberia, and Sierra Leone -- members of the so-called Mano River Union which has warned insecurity on the border represented a threat for the entire West African region -- would also add forces.
He did not give details.
Ivory Coast's southwest has been fraught with ethnic strife for decades, largely centered around land rights between indigenous tribes and the migrants who now make up the backbone of Ivory Coast's cocoa industry.
Tensions between the two groups have reignited since last year's disputed election sparked a civil war that toppled incumbent leader Laurent Gbagbo, paving the way for election winner Alassane Ouattara to take power.
The indigenous tribes in southwestern Ivory Coast and in nearby Liberia are believed to have supported Gbagbo, who was arrested in mid-April after fierce fighting.
Since Gbagbo's arrest, violence has simmered on.
In the most recent attack overnight on Thursday in the Tai region, officials and residents said the gunmen were likely former Gbagbo supporters from indigenous tribes, including the Guere, who had fled to Liberia during the war.
Some 19 migrant farmers from Niger and Burkina Faso and two government soldiers were among the 23 dead, Kouakou said.
"These were the youths from the villages that left for Liberia during the war and are starting to come back. They did this," said Issiaka Yameogo, a cocoa farmer in Zriglo, one of the villages attacked.
"We are afraid because Liberia is not far and they can come back again. But we are also worried because we can't easily return to the bush to harvest the cocoa, and it is the start of the new season and we must harvest."
Ivory Coast is the world's largest cocoa grower. The southwest accounts for some 90,000-120,000 tonnes of the annual crop, which this year is expected to top 1.4 million.
Father Laurentin Guei, from the Catholic mission in Tai, said the attack was the second in a month.
(Writing by Richard Valdmanis; Editing by Sophie Hares)