* French troops shoot one man, say they were fired on
* Witnesses say man was in group protesting lack of security
* French minister attends interim leader's swearing-in
By Emmanuel Braun
BANGUI, Jan 23 (Reuters) - Two people were shot dead in Central African Republic on Thursday in a clash that highlighted the scale of the task facing new interim President Catherine Samba-Panza as she took the oath of office.
Witnesses accused French forces of shooting dead one man who was among a group protesting against their lack of protection from attacks by Christian militias.
A French army spokesman acknowledged that the French force, known as Sangaris, had opened fire but said the soldiers had come under attack from gunmen.
Almost one million people, or a quarter of the population, have been displaced in the former French colony by clashes that began when mostly Muslim Seleka rebels seized power in a coup in March.
Christian self-defence groups, known as "anti-balaka" (anti-machete), have since taken up arms against them and the United Nations estimates that tit-for-tat violence has claimed more than 2,000 lives.
Thursday's violence in the PK12 neighbourhood on the northern edge of the capital Bangui started when anti-balaka fighters shot and killed one person at a camp for displaced Muslims waiting to leave the city, said Peter Bouckaert, a researcher for Human Rights Watch.
After the man was buried, angry protesters, some of them armed with machetes and other crude weapons, approached a French checkpoint, said Bouckaert, who is the rights campaigner's emergencies director.
"We didn't see the actual shooting (but) we saw (the demonstrators) bringing the body back from the frontline where they were protesting and they said: 'It's the French. It's the French,'" Bouckaert said by telephone.
Another man was wounded in the firing, Bouckaert added.
French army spokesman Colonel Gilles Jaron said a group of gunmen had "engaged with the Sangaris forces who responded. A member of the group was hit and his body was retrieved by the group". Jaron did not say whether any French soldiers were killed or injured in the incident.
Samba-Panza, the mayor of the capital, was appointed as leader on Monday, replacing Michel Djotodia, a former Seleka leader who stepped down on Jan. 10 amid intense international pressure. Samba-Panza has pledged to meet with armed groups in an effort to restore order..
Speaking in French newspaper "Le Parisien", Samba-Panza called for more foreign troops to calm violence, which the presence of a 1,600-strong French military mission and another 5,000 African Union peacekeepers has so far failed to quell.
French Foreign Minister Laurent Fabius was among regional leaders and government representatives who flew to Bangui on Thursday for Samba-Panza's swearing-in ceremony.
"We have already made a major effort. We never say never, but it's firstly up to the international community to mobilise now," Fabius said, referring to the possibility of Paris sending more troops.
French Defence Minister Jean-Yves Le Drian said on Thursday international forces faced a difficult task to end the deepening cycle of violence.
"Today crimes are still being committed. There is an unbelievable level of hatred. No doubt we underestimated the degree of hatred, the desire for vengeance among the Seleka and the anti-balaka militias," he told French TV channel iTele.
Some 500 additional troops pledged by European Union nations earlier this week will help to secure Bangui's airport and surrounding area, freeing up French soldiers for patrols in the capital and throughout the country, Le Drian said. (Additional reporting by Marine Pennetier in Paris; Writing by Matthew Mpoke Bigg; Editing by Joe Bavier and Gareth Jones)