A United Nations investigation into reported massacres in western Democratic Republic of the Congo confirms at least 535 civilians died in four separate attacks in Mai-Ndombe province in December.

“The team identified a total of 59 burial sites in two of the attacked towns, but do not rule out more sites,” said a statement from MONUSCO on Wednesday. Another 111 people were injured, while nearly 1,000 homes, churches, schools and medical centers were destroyed or looted.

About 16,000 people reportedly fled the Yumbi villages, with nearly half of them crossing the river to seek refuge in Congo-Brazzaville, according to information from the UN refugee agency, UNHCR.

The attacks were attributed to longstanding communal tensions, but in addition to existing rivalries there were reported political disagreements as DR Congo faced its December 30 elections. The Batende were supporting Emmanuel Ramazani Shadary, while the Banunu preferred opposition candidates in a contest that Felix Tshisekedi of the Union for Democracy and Social Progress (UDPS) party won with 38.6 percent of the vote.

Voters in Yumbi were unable to cast their votes, as the electoral commission building was among those totally destroyed – a decision that in turn added to the Congo’s tensions.

Each mass grave discovered so far likely contains dozens of bodies, while there were more than 40 other individual graves unearthed, according to the fact-finding mission working with local authorities.

MONUSCO said it “strongly condemns” the violence and is calling for a thorough investigation. The mission said it was ready to support the Congolese authorities to “bring justice to the victims, and promote reconciliation between the two communities.”

Image: UNHCR file