At least 12 civilians were killed and 30 wounded, including children, in an attack northwest of the Central African Republic capital Bangui.

The UN said Christian armed groups known as "anti-balaka" appeared to have targeted Peul herders, who are mostly Muslim.

In a statement on Tuesday, Amy Martin, head of the UN Office for the Coordination of Humanitarian Affairs in Bangui, said the attack occurred on Monday.

Martin said the incident was one of a number in recent days, including fighting on Tuesday just 45km north of Bangui.

"It looks much more organised just than community defence groups," she said, of the armed group that has formed to counter abuses by former rebels, known as Seleka.

BINUCA, the UN office in Bangui said unidentified armed men had targeted Boali, about 60 miles from the capital during the weekend.

While not providing details on who was responsible, the UN warned has warned against the tensions between communities leading to "a climate of increasing violence" in the country.