Gunshots and heavy weapons fire erupted late on Tuesday between rival factions within Ivory Coast's army at military bases in its second largest city, Bouake, residents and soldiers said.
Bouake was the epicenter of several months of army mutinies last year that spread to cities and towns across Ivory Coast, forcing the government to cave in to demands for bonus payments and promotions.
"I'm hearing very intense shooting from machine-guns," said Bouake resident Georges Kouame. "There are also explosions from heavy weapons."
The outbreak of renewed violence follows days of tensions in Bouake between participants in last year's mutinies and members of an elite military unit, known as the CCDO. At least one person died in the wake of clashes there on Friday.
Former mutineers told Reuters they believed the CCDO members had been sent to Bouake to spy on them.
"At the moment we are surrounding the CCDO camp and there is an exchange of gunfire," said one of the mutineers' leaders. "They must leave the city or we will force them to leave."
A regional security source, who asked not to be named, said the government had earlier in the day dispatched around 200 soldiers to reinforce positions in Bouake.
Ivory Coast, the world's top cocoa grower, has emerged from a decade-long political crisis as one of Africa's fastest growing economies and a darling of international investors.
However, last year's instability laid bare the dangerous divisions that still persist within an army cobbled together from rival rebel and loyalist factions at the end of a 2011 civil war.