Rebels in Central African Republic have kidnapped, burnt and buried alive "witches" in public ceremonies, exploiting widely held superstitions to control areas in the war-torn country, according to a leaked United Nations report.

The report by U.N. human rights officers, seen exclusively by the Thomson Reuters Foundation, contains graphic photographs of victims tied to wooden stakes being lowered towards a fire as well as the charred torsos of those subjected to the ritual.

The torture took place between December 2014 and early 2015 under instruction from leaders of the mainly Christian "anti-balaka" militia that has been fighting Muslim Seleka rebels across the country for more than two years, said the report.

Central African Republic was plunged into sectarian violence when Muslim rebels briefly seized power in the largely Christian country in March 2013, with escalating violence on both sides creating lawlessness nationwide outside the capital Bangui.

While belief in witchcraft is common throughout Africa, U.N. researchers said it appeared Christian rebels had used these superstitions to intimidate, extort money and exert authority over lawless areas.

"Sorcery is firmly entrenched in [Central African Republic] and ... the absence of state authority creates a breeding ground for a sort of popular justice twisted by anti-balakas to its benefit," said the researchers.

The report, produced by a team working for the U.N.'s stabilisation mission known as MINUSCA, said 13 attacks against victims aged between 45 and 70 are said to have taken place near Baoro in Nana-Mambere, one of 14 prefectures in the country.

Nana-Mambere in the country's south west has been ravaged by violent clashes between rival rebel groups with U.N. peacekeeping forces unable to restore calm.

The report identifies three leaders of the anti-balaka faction in Nana-Mambere present during the alleged torture sessions.

Victims were ordered, sometimes at gunpoint, to pay between $30 to $80 in bribes to avoid being tied up or burned. Nearly two thirds of people in CAR live on less than $1.90 a day, according to World Bank data.

Witchcraft is still punishable by law in Central African Republic and jail terms are commonly handed out as punishments with some reports saying half of the country's jails are taken up with those accused of witchcraft.

In September 2010, the High Court in the capital Bangui found four people, including two children aged 10 and 13, guilty of witchcraft and charlatanism, Amnesty International reported.

Interim justice minister Dominique Saïd Panguéndgi, who like all members of the transitional administration is barred from running in the upcoming elections, said judicial reform regarding witchcraft had been slow and not deemed a priority.

"Witchcraft is a question of belief, so we need to train magistrates," he said in his office in Bangui. "But at least the debate [about witchcraft] has begun."

Reuters