French troops exchanged gunfire with militiamen in the Central African Republic (CAR) as defence minister Jean-Yves Le Drian arrived in Bangui from Paris to hold talks with President Michel Djotodia.
Le Drian inspected French soldiers who had been deployed as part of an UN-backed mission to quell violence between Christian and Muslim militias that have pushed the country into chaos. France has deployed some 1,600 troops in CAR to bolster African Union peacekeepers tasked with disarming opposite militia groups.
"The spiral of confrontation has brutally worsened and a humanitarian crisis is starting to add up to the security crisis," Le Drian said.
Le Drian added the country was "adrift", Le Parisien said.
A few hours later, French forces backed by a helicopter opened fire on former rebels in Bangui's Miskine neighbourhood.
More than 500 people were killed last week in clashes between ex-rebels with the mostly-Muslim Seleka coalition and their Christian rivals known as "anti-balaka" ("machete" in the local Sango language).
Security in CAR deteriorated after former president Francois Bozize was toppled by the Seleka rebel coalition led by Djotodia in March. Djotodia subsequently appointed himself as CAR's first Muslim president.
Seleka was disbanded but groups of former rebels remained armed and embarked on lootings and sporadic attacks against Christians, who in turn created their own self-defence militia.
Half of the CAR's 4.5m population is Christian, while about 15% is Muslim. Both factions have been accused of atrocities against the population.
The slaughtering of a Christian taxi driver in Miskine sparked the latest confrontation between machete-wielding youths.
In a separate incident African Union peacekeepers rescued a group of Muslims who were besieged inside a church by an angry mob.
Two French soldiers were shot dead by gunmen in Bangui earlier this week.
Aid officials said that 100,000 people have been displaced.