At least 48 people were killed in clashes between Christian and Muslim-dominated militias in a restive Central African Republic town last week, according to an internal UN report seen Monday by AFP.
The death toll had previously been reported as 37, including two priests, in the country's latest surge of sectarian violence.
The bloodshed was sparked in the central town of Alindao on Thursday between Christian militiamen, known as anti-Balaka, and the Union for Peace in CAR (UPC) Muslim militia.
The town's church and a camp for displaced people were torched. Pictures seen by AFP show burnt bodies in the fire.
Other than the two priests, it has not yet been possible to confirm whether those killed were civilians or armed fighters.
More than 20,000 people have been displaced by the violence, according to the UN.
One of the world's poorest nations despite a rich supply of diamonds and uranium, the CAR has struggled to recover from a 2013 civil war that erupted when President Francois Bozize, a Christian, was overthrown by mainly Muslim Seleka rebels.
In response, Christians, who account for about 80 percent of the population, organised vigilante units dubbed "anti-Balaka" in reference to a local machete.
UN Secretary General Antonio Guterres on Saturday said the latest attack was attributed to the UPC militia, which has its roots in the Seleka group.
Looting and violence
However the UPC accused "both Muslim and Christian bandits" of being behind the incident."
The UPC has dispatched one of its units to stop looting and violence," the group said in statement on Monday.
Alindao is a UPC stronghold and has witnessed chronic fighting in recent months that has also killed two UN soldiers and a humanitarian aid worker.
The town lies on a critical route traversing the south and east of the country and is in the heart of a region numerous gold and diamond mines that have helped fuel the conflict.
The UN has warned of a "disastrous" humanitarian situation in the region, which it said was under the control of armed groups.