French forces kill fighters as more troops arrive in Central African Rep.

French soldiers have killed unidentified fighters in the capital of the Central African Republic near the airport, a French army spokesman told the Reuters news agency.

The army shot the men in clashes early on Thursday in Bangui, the official said, shortly before the U.N. gave a green light to the mission to stabilize the country. France began sending reinforcements within hours of the U.N. vote on Thursday.

"Armed gunmen in pick-up trucks fired on French positions at the airport yesterday morning," French army spokesman Gilles Jarron said on Friday. "We fired back. The pick-up was destroyed and the gunmen were killed," he said, though he could not immediately say how many people were killed.

The U.S. State Department estimates that nearly 400,000 people have been displaced and 68,000 have fled to neighboring countries since Seleka leader and interim president Michel Djotodia lost control of his loose coalition of local leaders.

The violence has increasingly pitted Seleka's mainly Muslim fighters against Christian militias. Christians make up half the population and Muslims 15 percent.

France, which already maintained a peacekeeping force in the country, was spurred to action after armed Christian fighters raided Muslim neighborhoods on Thursday, leaving about 100 people dead. French officials have insisted that the 1,200-troop injection will aim to bring a modicum of security to Bangui, where people now fear to leave their homes, and to support an African Union-led force.

"You have to secure, you have to disarm," Jean-Yves Le Drian, French defense minister, told Radio France Internationale. "You have to ensure that the vandals, the bandits, the militias know they can't use the streets of Bangui for their battles."

The British government was also flying in military equipment Friday to the Central African Republic on a C-17 plane to help with France's intervention. Foreign Secretary William Hague said Britain was "determined to play our part in helping to address the violence."

With Bangui hovering near anarchy, the streets were empty except for military vehicles and the trucks favored by rebel forces who now claim control of the government. Nine unclaimed bodies sprawled in front of the parliament building on Friday — local Red Cross workers didn't dare retrieve them or other bodies left to decay outside.

Since thousands of armed Muslim rebels invaded Bangui in March, the city remains awash in weapons and recent attempts at disarmament have yielded few results.

Al Jazeera with wire services