The headquarters of the party of former Ivorian president Laurent Gbagbo were sacked on Monday, injuring three people, a spokesperson said.
Confidential documents, including financial registers, were stolen as a group of around 20 youths "literally trashed" Gbagbo`s former officers, Frank Anderson Kouassi, spokesman for the Ivorian Popular Front (FPI), told AFP.
An AFP photographer at the headquarters said rooms were littered with scattered documents, smashed computers and printers, broken glass and upturned furniture.
A party official suggested the perpetrators may have been youth FPI activists.
"It is an internal thing, we have no illusions," the official said. "Although we do not exclude any hypothesis."
The party of the former Ivorian president is torn over its participation in the new Independent Electoral Commission, which is responsible for organising next year`s crunch presidential vote.
Kouassi said that a closed-doors party meeting over the weekend had "almost degenerated into a fight" after repeated arguments.
Gbagbo ruled the Ivory Coast from 2000 until he was arrested at his presidential bunker in Abidjan in 2011.
He is currently in custody awaiting trial at the International Criminal Court on charges of crimes against humanity.