GENEVA — The UN's top human rights body on Monday appointed an expert to probe violations in the Central African Republic , as UN chief Ban Ki-moon called for immediate action to stem the violence.

"The CAR is in free-fall... We must act together, and act now, to pull CAR back from the brink of further atrocities," Ban said in a statement read by the acting head of the UN mission in Geneva Michael Moeller, warning that the country was caught in "a crisis of epic proportions."

He spoke at a special session on the violence-torn country before the UN Human Rights Council, which concluded Monday with the appointment of Marie-Therese Keita Bocoum of the Ivory Coast to investigate a litany of rights violations in the country.

Keita Bocoum, who has served as the UN Special Rapporteur for Burundi and has also headed the human rights section of the UN's office for West Africa and of its operation in Darfur, was asked to make an urgent visit to Central Africa and brief the council on her findings.

The session, which also unanimously adopted a resolution calling on the international community to meet the urgent humanitarian needs in the CAR, concluded shortly after Bangui mayor Catherine Samba-Panza was elected interim president.

Central Africa's first woman leader will be tasked with trying to restore peace in the former French colony, where thousands of people have been killed in sectarian violence between Christians and Muslims.

Strongman president Michel Djotodia stepped down on January 10 amid intense international pressure over his failure to stem the bloodshed, which the UN has warned could turn into genocide.

"A strong and concerted nationwide effort is essential to stop CAR crossing the tipping-point into an all-out sectarian conflict," UN human rights chief Navi Pillay told the council in Geneva Monday.

Central African ambassador to the UN in Geneva, Leopold Ismael Samba, also warned the conflict could escalate into "genocide".

"And this risk will escalate if nothing is done to reestablish the attributes of the state and help provide the population with a minimum," he told the council Monday, calling for "a Marshall Plan" to rescue his crisis-ridden country.

A team of UN investigators who spent nearly two weeks in the volatile and impoverished country last month have also reported finding a litany of gross human rights violations, including killings, kidnappings, torture and rape.

"The mission received consistent, credible testimony and photographs supporting allegations that anti-Balaka (Christian militias) mutilated Muslim men, women and children, before or after they were killed, including upon the breasts of female victims and genitals of male victims," Pillay said.

The majority Christian country has descended into chaos and sectarian unrest since the mainly Muslim Seleka rebel group overthrew president Francois Bozize and installed Djotodia in his place last March.

More than 1,000 people are believed to have died last month alone with almost one million people driven from their homes, including half of the residents of the capital, Bangui.

Some 2.6 million people, or about half of Central Africa's population, are in need of humanitarian assistance, according to the UN.

European Union foreign ministers meanwhile agreed Monday to send hundreds of troops to the country in a rare joint military mission.

The mission, which will deploy in and around the capital and last up to six months, is expected to involve the rapid deployment of a force numbering anywhere between 400 and 1,000.

The troops will help back 1,600 French soldiers and the African Union's MISCA force, which currently has 4,400 troops on the ground.

International donors also pledged $496 million (365 million euros)