Heavy gunfire erupted early on Saturday near the main military camp in Ivory Coast's second largest city, Bouake, where disgruntled soldiers launched an uprising a day earlier over salaries and bonuses, a resident and a soldier said.

"The shooting is very heavy right now at the third battalion. I'm nearby and I hear it like it was right next to us," resident Konan Benoit told Reuters news agency by telephone, as gunfire could be heard on the line.

The renegade soldiers have controlled the city of around a half million residents since taking up positions at key entry points early on Friday.

The army has sent reinforcements to Bouake but the defence minister said in a statement late on Friday that the government was prepared to listen to the soldiers' grievances.

It was not immediately clear what provoked the gunfire, but a member of the uprising said soldiers had seen what they considered suspicious movements outside the camp in Bouake.

"This is gunfire to discourage them," the unnamed soldier said.

Similar mutinies also occurred in two of the West African nation's other main cities on Friday as the movement appeared to spread.