BOUAKE - Heavy gunfire rang out Monday in Abidjan and Bouake, Ivory Coast's two biggest cities, witnesses said, as a mutiny by disgruntled soldiers demanding bonuses entered its fourth day.

It was the latest in a series of armed protests which have gripped the country since January, with troops angered by an unresolved dispute over wages and demanding the government of President Alassane Ouattara pay up.

"This is not a coup. We want our bonuses. The president signed a paper saying he agreed with our bonuses. When he pays up, we'll go home," said a spokesman for troops at Bouake barracks, the centre of the latest four-day protest. "We'll fight to the end. We won't lay down arms," he said, speaking on condition of anonymity from the city where the protest movement began earlier this year. "8,500 of us brought Ouattara to power, we don't want him to leave but he's got to keep his word. It's that simple," he added as a group of soldiers, some wearing masks, let off a rattle of gunfire.

Ouattara took office in 2011 after months of deadly election violence in which more than 8,000 rebels supported him against troops backing ex-head-of-state Laurent Gbagbo, who refused to concede defeat at the ballot box. Many of the rebels subsequently joined the regular army, which currently numbers some 22,000 troops. Early on Monday heavy gunfire was heard at two military camps in Akouedo in the east of the economic capital, Abidjan, which together form the country's largest military barracks, a resident living nearby said. Access roads into Akouedo were closed, preventing residents from the east of Abidjan from entering the city, an AFP reporter said. Shots were also heard from Gallieni camp in the city centre.

Sustained gunfire also rang out in Bouake, the second-largest city, where one person died on Sunday from bullet wounds.

The situation was also tense in Man in the west and Bondoukou and Daloa in the centre of the country, where sporadic shooting could be heard.

Armed forces chief of staff General Sekou Toure on Sunday said a military operation was under way "to re-establish order" and made a televised appeal to the disgruntled soldiers to return to their barracks. But there was no immediate sign of any troop movements on the road between Abidjan and Bouake.

Mutinous former rebels often fire in the air to express their anger over the non-payment of bonuses by the government. The African Development Bank advised its employees in Abidjan to stay at home, warning that the security situation remained unclear.

Under a deal negotiated with the government in January following the initial protest, the ex-rebels were to be paid bonuses of 12 million CFA francs (18,000 euros) each.  They were given a partial payment of five million francs with the remainder to be paid starting this month, according to sources among the protesting soldiers. But the government has struggled to pay the promised money.  Bouake, which was at the epicentre of the January mutiny, served as the rebel headquarters following a failed coup in 2002 which split Ivory Coast in half and led to years of unrest.

The former star French colony has since been slowly regaining its credentials as a West African powerhouse and a haven of peace and prosperity. But falling cocoa prices have severely crimped the government's finances. The current round of trouble began late Thursday when a soldier presented as a spokesman for the former rebels said they wished to apologise to Ouattara for the January mutiny and were renouncing their demand for huge payouts.

But the 'apology', which was delivered in a televised ceremony, was viewed with scepticism by many of the mutinous soldiers.

"We don't know if the delegates who were sent to Abidjan (for the ceremony) betrayed us, if they are corrupt or if they were taken hostage over there," said Sergeant Yacouba Soro, one of those protesting in Bouake. "But we have not given up, that's clear."

Last year, the government unveiled an ambitious plan to modernise the military, part of which would involve the departure of several thousand men, particularly ex-rebels, who will not be replaced.