Six Red Cross workers were killed last week amid violent clashes in southern Central African Republic, the International Committee of the Red Cross (ICRC) said.
The bloodshed occurred last Thursday at a health centre in Gambo, 70 kilometres (45 miles) from the town of Bangassou, where nine peacekeepers have been killed since early May, it said in a statement.
The organisation on Tuesday gave a toll of three dead among its local staff, and said "dozens" of other people had also been killed.
Concurring sources said the fighting was between so-called self-defence militias and members of a group called the Union for Peace in Central Africa (UPC), part of a Muslim-majority rebel organisation called the Seleka.
The Seleka overthrew former president Francois Bozize in 2013. The rebels themselves were swiftly ousted, leading to a wave of violent reprisals against the Muslim population by the Christian anti-Balaka militia.
On Monday, Stephen O'Brien, head of the UN Office for the Coordination of Humanitarian Affairs (OCHA), said there were "early warning signs of a genocide" in Central African Republic.
On Tuesday, the agency said 24 people, including 14 civilians, died in northwestern Batangafo from July 29 to August 2.
Ten people were killed in a southern village near Alindao on August 4, according to OCHA, while fighting in Ngaoundaye, near the borders with Cameroon and Chad, killed at least 10 and forced around 7,000 people to flee the area, several sources told AFP.
UN peacekeeping chief Jean-Pierre Lacroix last week said he was considering sending a request for more troops for the 12,500-member force MINUSCA.
The government of President Faustin-Archange Touadera, who was elected last year, remains in control of Bangui but its authority is weak outside the capital.
The UN has received only 24 percent of the $497 million (400 million euros) it has requested in humanitarian aid for the country.