* U.S. authorizes use of transport planes to aid French effort
* International Criminal Court calls for an end to attacks on civilians
* Life resumes in parts of Bangui as scale of killing emerges
By Emmanuel Braun
BANGUI, Dec 9 (Reuters) - The French army said it has restored some stability in the capital of Central African Republic after battling gunmen on Monday in an operation to disarm rival Muslim and Christian fighters responsible for killing hundreds since last week.
Shooting erupted near Bangui's airport in the morning when gunmen refused to hand over weapons and French forces later came under attack by former rebels in the city centre, but by evening there were no armed groups on the streets, the army said.
"There are no more patrols by armed groups in the city and the population is no longer threatened by the terror that these groups caused," said Colonel Gilles Jaron, spokesman for the French army joint staff in Paris.
"The spike in violence has gone down and we have returned to a more stable situation. We are still deployed in Bangui to carry out our mission," Jaron said.
Paris boosted its military presence to 1,600 troops over the weekend as waves of religious violence swept its former colony.
At least 465 people have been killed in Bangui alone since Thursday, according to Red Cross officials.
In an audio message to the country's people, President Barack Obama pledged U.S. support for efforts by France and African countries to restore security and protect civilians.
"You, the proud citizens of the Central African Republic, have the power to choose a different path," Obama said in the message. He said Muslim and Christian leaders, "are calling for calm and peace. I call on the transitional government to join these voices and to arrest those who are committing crimes."
U.S. Defense Secretary Chuck Hagel has authorized military transport aircraft to carry troops to the country from Burundi to support the French-led effort, a Pentagon spokesman said.
Hagel authorized the use of the planes on Sunday after being asked for airlift assistance by French Defence Minister Jean-Yves Le Drian, the spokesman said in a statement.
Central African Republic has spiralled into chaos since mainly Muslim Seleka rebels seized power in March and embarked on months of looting, raping and killing. Seleka's leader, Michel Djotodia, installed as the interim president, has lost control of his loose band of fighters.
The International Criminal Court's chief prosecutor said any party involved in the violence could be prosecuted.
ATTEMPT TO INTIMIDATE
Christian militias and gunmen loyal to ousted president Francois Bozize attacked Bangui on Thursday, the same day the U.N. Security Council authorised France to use lethal force to help African peacekeepers already struggling to restore order.
In an early test of France's resolve, its troops traded fire with gunmen near the airport on Monday morning.
"Many armed elements who held positions in Bangui have left their positions to go back to their barracks," said Jaron, who called the incident "insignificant".
However, French troops again came under attack later in the day in the PK 5 neighbourhood from suspected Seleka fighters.
"It was an attempt to intimidate. We responded with 20mm cannon, then sent in a platoon to carry out clean-up operations," said Captain Guillaume Fresse, spokesman for the French forces in Bangui.
The French operation is running smoothly though its most difficult phase lies ahead, France's ambassador to the United Nations, Gerard Araud, told reporters in New York.
"The French forces have reestablished law and order in Bangui, even if there is still some looting in the periphery," said Araud, president of the U.N. Security Council this month, after briefing the council on the situation.
With French forces on checkpoints and on patrol, crowd violence erupted in several districts of Bangui.
In the Castor neighbourhood, a Reuters reporter saw a crowd attack a man they accused of being a disarmed Seleka fighter after French soldiers removed weapons from a house there and then left.
At a mosque in the PK 5 neighbourhood, the resident imam showed journalists the bodies of two men who he said had been beaten to death by Christians.
French troops have been broadly welcomed in a city struggling to emerge from a period that saw fighters, both Christian and Muslim, go door-to-door killing civilians.
As French warplanes and helicopters flew low overhead, residents reappeared on the streets and some shops and market stalls reopened for the first time since last week.
"Yesterday we couldn't even come here to cross this road because the Seleka came and set up a base here," said a woman who gave her name only as Armelle. "Thank God the French came. If there's peace, things will get better."
However, the United Nations said it had counted some 72,000 people displaced by the violence staying in various sites in Bangui, including at the airport, where French troops and African peacekeepers have their base.
"There are still conflicts in some neighbourhoods. There's still killing," said Amy Martin, head of the U.N. aid agency OCHA in Bangui. "For now, we don't have the feeling that people are ready to go home.
Information began to trickle in from parts of the country cut off from the capital since last week.
A humanitarian worker in the town of Bossangoa said the number of dead there from several days of violence between Seleka and Christian "anti-balaka" militias had risen to 38. France has sent two companies of troops to the town, Araud said.
In Bozoum, in the northwest, U.N. officials received reports of dozens of dead, and there was also violence in the nearby town of Bocaranga.
Humanitarian agencies and rights groups said the final toll was likely to be much higher.
(Additional reporting by Marine Pennetier in Paris, Joe Bavier in Abidjan, Matthew Mpoke Bigg in Accra, Bate Felix in Casablanca, Phil Stewart and Jeff Mason in Washington, David Alexander in Doha and Louis Charbonneau in New York; Writing by Matthew Mpoke Bigg; Editing by Ralph Boulton and Paul Simao)