U.S. Ambassador to the United Nations Samantha Power is in the Central African Republic to discuss the country's increasingly brutal violence with government officials and civil society leaders.
Power arrived in the capital, Bangui, on Thursday for a one-day visit. She told reporters during a stop in Nigeria that disarming the groups behind the fighting is critical to stabilizing the country.
"The violence has been vicious, it has been directed almost entirely against civilians, and it has been increasingly sectarian. And only with this disarmament do we think that that violence can come to an end."
The CAR slipped into chaos after mostly Muslim rebels, known as Seleka, toppled president Francois Bozize in March. Months of looting and killing have brought retaliation by Bozize allies and Christian militias known as anti-balaka.
Human rights groups expressed renewed alarm over the situation Thursday.
Amnesty International said more than 1,000 people had been killed in Bangui since violence flared earlier this month. The death toll is significantly higher than what had been reported by relief organizations.
Human Rights Watch issued a report saying the Christian militias have committed atrocities against Muslims in a cycle of violence that "threatens to spin out of control."
The group highlighted alleged brutality by the militias in Ouham province, where it said fighters have slit the throats of women and children.
Peter Bouckaert, emergencies director for Human Rights Watch, says there is a high potential for more mass violence.
"We documented many cases in which both Christians and Muslims were targeted because of their religion and their attackers made statements like, 'We will kill all the Muslims in the country.' We've documented where children as young as three years old had their throats cut by the attackers. So we're talking about extreme violence and communal violence. And once that communal violence sets in, it's very difficult to stop."
French and African Union troops in Bangui are attempting to stop the violence and restore order.
The African Union recently boosted the planned number of troops in an African-led support mission in CAR, known as MISCA, from about 3,600 to 6,000 troops.
The transfer of troop authority from the Economic Community of Central African States to MISCA is taking place on Thursday.
In an interview with VOA , AU spokesman El Ghassim Wane said MISCA's leadership has already begun work in Bangui.
The U.N. refugee agency says fighting in the capital has displaced more than 200,000 people this month.
The U.N. humanitarian office says an estimated two million people are need of humanitarian assistance, with one million people suffering from lack of food.