BOUCA -- About a dozen Muslim armed fighters rolled up to the Catholic mission in their pickup truck and delivered an ominous message to the hundreds seeking refuge on church grounds: Leave the premises by morning or face death.

Ismael Hadjaro, a self-proclaimed colonel in a rebel movement that overthrew Central African Republic's president earlier this year, accused the mission and its staff of harbouring armed Christian combatants.

"If you are not gone by 8 o'clock tomorrow morning we will come back and shoot you and burn down the mission," he told the nun running the mission, according to a witness. "You're making this a religious war."

Frantic phone calls followed and soon soldiers from a regional peacekeeping mission showed up to guard the Catholic mission, where church officials and aid workers insist they are merely trying to protect civilians. Most of the people sheltered there are women and children, according to Lewis Mudge, a researcher with the Africa division of Human Rights Watch who witnessed the colonel's threat in Bouca last week.

France's foreign minister has warned that its former colony in central Africa is "on the verge of genocide" as attacks mount across the country's remote northwest between the mostly Muslim fighters from Seleka, who ousted the president in March, and Christian militias that have emerged to defend towns and in some cases attack Muslim civilian communities. To try to avert further violence France has pledged to send 1,000 troops to Central African Republic to help boost security before an African Union-led peacekeeping mission is fully up and running.

The situation in Bouca has been particularly dire since early September, and fresh clashes in late November prompted the threat against the Catholic mission. Forty-three bodies have been buried in recent weeks in Bouca, about 180 miles (290 kilometres) north of Bangui, the capital, according to the International Committee of the Red Cross.

Hundreds of homes in Bouca have been burned to the ground and those who haven't fled to the Catholic mission have taken shelter in the fields outside town.

"My house was looted and burned by the Seleka forces, and like many here I fled into the bush," says Nathanael Wandji, the director of the local Red Cross in Bouca. "We need to restore peace here quickly. The situation is becoming more and more dramatic."

The area around Bouca is home to a growing Christian militia movement known as the anti-balaka. The fighters -- armed in some cases only with artisanal hunting rifles -- rose up earlier this year in opposition to the wave of attacks by Seleka rebels. The rhetoric has taken on an increasingly sectarian tone in a town where Christians and Muslims had lived together in relative peace for generations.

The ex-Seleka forces want to restore order in Bouca and they know that not all Christians support the militias, said Mahadji Maamate, a spokesman for the rebel leader who threatened the church.

"The anti-balaka fighters are against Muslims and they don't want Muslims living among them," Maamate told The Associated Press during a recent visit to Bouca. "They have killed poor Muslims and burned their children."

Outside Bouca, the anti-balaka adorn themselves with talismans -- or gris-gris -- to give them spiritual protection from the enemy's bullets. Their weapons are mostly primitive artisanal hunting rifles, though some cart AK-47s stolen from dead Seleka fighters and others have weapons that appear to come from the national army.

Many are motivated by vengeance and say their relatives have been killed by Seleka forces.

"The rebels killed my parents and my wife -- now it's my turn to kill them," said one anti-balaka fighter brandishing a weapon and who refused to give his name.

The violence first ignited in Bouca on Sept. 9, when Christian militia fighters attacked a Muslim neighbourhood, setting homes ablaze. Reprisal attacks were soon launched by the Seleka rebels and among the victims was a humanitarian worker accused of collaborating with the anti-balaka, according to Amnesty International. It is believed to be the single deadliest day of violence confirmed in the northwest since the conflict began, with 115 Christians and 38 Muslims killed in the fighting, Mudge said.

Even as the community maintains an uneasy peace, people are still dying from malaria and other diseases because of a lack of access to health care.

"The fighting in Bouca is indicative of how horrific violence is engulfing the Central African Republic," said Sylvain Groulx, head of mission for Medecins Sans Frontieres, or Doctors Without Borders, in Central African Republic. "We are extremely concerned about the living conditions of the displaced, who are overcrowded in churches, mosques or schools, or living in the bush with no access to health care, food or water. Much more needs to be done and it needs to be done now."