Twenty-five people were killed, six of them gendarmes, in two days of violence around the town of Bambari in the troubled Central African Republic, the UN force MINUSCA said Saturday.
Six police and four civilians were killed in an ambush by armed men Friday morning, while on Thursday, 15 people died in fighting on the town's outskirts between the former Muslim Seleka militia and Christian vigilante groups known as "anti-balaka" (anti-machete), it said in a statement.
In a further incident, anti-balaka fighters on Friday attacked eight members of MINUSCA as they were heading to Bambari airport, the force said. A seven-year-old child was injured.
The UN force said there had been a "rise in tension in certain regions," citing "confrontation between armed elements of the ex-Seleka and anti-balaka" groups.
It called on the armed groups to end "the cycle of attack and reprisal."
Bambari lies in central CAR, about 250 kilometres (150 miles) northeast of the capital Bangui.
The bloodshed is the latest bout of violence to strike the CAR, a former French colony that is one of the world's poorest countries.
It occurred in the runup to the formal end on Monday of a French military mission, Operation Sangaris, sent to help the UN stabilise the country.
MINUSCA is seeking to support the administration of President Faustin-Archange Touadera, who was elected in February.
The CAR's descent into sectarian bloodshed began after the March 2013 ouster of president Francois Bozize, a Christian, by the mostly Muslim Seleka rebel alliance.
This triggered revenge attacks and a spiral of atrocities between Christian and Muslim groups in which thousands were slaughtered and around a tenth of the population of 4.5 million were displaced.
Earlier this month, 30 people were killed and 57 wounded when Seleka fighters staged an attack in the central town of Kaga Bandoro.
A few days later, 11 people were shot dead in a camp for displaced people in Ngakobo, northeast of Bangui.
On October 24, four civilians were killed when protests against the UN peacekeepers, called by a coalition of civil society groups angered by the rise of armed militias, turned violent.