Gunfire was heard early on Monday in Ivory Coast's two main cities, according to witnesses, as the military pressed an operation aimed at ending a mutiny by soldiers demanding bonus payments.

In the commercial capital of Abidjan, shots were heard from two military camps in the east of the city, a nearby resident told the Reuters news agency. Frequent gunshots were also heard in the country's second city of Bouake.

"I've been hearing the sound of Kalashnikovs and a heavier weapon," one Abidjan resident told Reuters.

"That began at around 5am (05:00 GMT) and it's lasted an hour. It's intense," added the resident who lives near the US embassy and the presidential residence.

"There was heavy shooting at the northern entrance to the city and in the city centre. It's calmed a bit but we're still hearing gunfire," said one Bouake resident. A second resident confirmed the shooting.

The mutineers often fire in the air to express their anger over the non-payment of bonuses.

READ MORE: Mutinying soldiers seal off Ivory Coast's Bouake

"Negotiations on Sunday evening to convince the mutineers to lay down their weapons failed and the situation remains tense," Al Jazeera's Ahmed Idris, reporting from the outskirts of Abidjan, said.

“The situation is dangerous in terms of what will happen if a full-blown confrontation erupts between loyal forces and mutineers - the civilian population will be caught in the crossfire."

Six people were wounded by gunfire on Sunday, and one of three protesters shot and wounded on Saturday in Bouake died of his wounds.

The unrest came as authorities launched a military operation "to re-establish order" after soldiers who staged a mutiny on Friday over bonus payments refused the army's demand to disarm.

The mutineers, most of them former rebel fighters who fought to bring President Alassane Ouattara to power, sealed off Ivory Coast's second-largest city, Bouake, and used gunfire to break up protests against the revolt.

Their revolt began in Bouake when a spokesman for the group dropped demands for extra pay promised by the government during negotiations to end a previous mutiny in January.

Under a deal negotiated with the government in January, the soldiers were to be paid bonuses of 12 million CFA francs (18,000 euros) each, with an initial payment of five million francs that month.

The 8,400 mutineers were due to get the rest of the sum this month.

But the government has struggled to make the payment, with a budget hit by the collapse in the price of cocoa, Ivory Coast's main export.

Last year, the government unveiled an ambitious plan to modernise the 22,000 strong military, part of which would involve the departure of several thousand men, particularly ex-rebels, who will not be replaced.