Recent deadly clashes involving Ivory Coast ex-rebels highlight the most urgent and difficult task facing President Alassane Ouattara -- reforming the armed forces without alienating the men who swept him to power.

What could have remained a minor altercation between a soldier from the Republican Forces of Ivory Coast (FRCI) and a local youth in Sikensi near Abidjan Monday, degenerated into inter-ethnic clashes that left four dead and 15 wounded.

The scrap pitted members of the southern Abidji tribe against FRCI fighters and members of the northern Malinke tribe.

A similar scenario a week earlier in the western region of Vavoua left six dead, as Ouattara grappled with the inevitable challenges of reining in victorious rebel-turned-government forces.

The backbone of the west African country's army consists of northern former rebels who helped Ouattara gain the upper hand in his deadly and protracted election dispute with former president Laurent Gbagbo.

Nord-Sud, a newspaper close to former rebel chief Guillaume Soro, now prime minister, blamed the recurring violence on provocation from Gbagbo's camp but admitted the FRCI were not exempt from blame.

The latest incidents show that the division between north and south, Gbagbo and Ouattara supporters, Malinke and southern tribes is deep, one expert said on condition of anonymity.

"Ethnic and political differences are raw: reconciliation will take time," the expert said.

The most immediate conundrum is the de facto integration into the regular army of thousands of former rebels who need to be given a job.

"All of them cannot remain in the army. When they are given the boot, some will become carjackers, others thieves and the rest will just be on the market to be recruited whenever the political temperature rises. It's a real cancer," the source said.

After the deadly violence in Vavoua, Ouattara -- who also owes his job to Western diplomatic and military support -- vowed a "zero tolerance" policy when dealing with indiscipline within army ranks.

He set up a military police headed by charismatic ex-rebel commander Zakaria Kone to make former Forces Nouvelles (FN) rebels toe the line.

Soro, who is also Ivory Coast's defence minister, has promised to tour army barracks in January and organise a national conference early next year to outline a reform of the armed forces.

But eight months after the electoral dispute that left some 3,000 people dead and brought the country back to the brink of civil war, the government's announcements only reveal that everything remains to be done.

The new regime "doesn't know where to start to tackle this problem," torn as it is between financial constraints and the need to reward men who see themselves as liberators, an official close to the case said.

The violence is "the strongest case for keeping Soro as prime minister," the source added.

That option is not to the liking of former President Henri Konan Bedie, who is Ouattara's main ally and was seen as entitled to the job.

The International Crisis Group said in a report in December that the conundrum facing the country was all too predictable.

"Having endorsed the installation of a democratically elected president by ex-rebel forces, the international community could have predicted the difficulty of pressing them to restore state authority rather than celebrate victory and continue abuse," the Brussels-based think tank said.

But it also argued that the issue was too important to be left to anyone other than Ouattara himself.

"President Ouattara must personally prioritise the overhaul of the defence sector, and avoid delegating responsibility for this essential reform," ICG said in its report.