The clashes erupted on Friday in the eastern province of Ituri, between the Hema and Lendu ethnic groups, resulting in at least 23 Hema being “massacred”, said Hema spokesman Hadji Ibrahim Ruhigwa Bamaraki, denouncing the deaths as “a terrorist aggression”.
“Hundreds of homes have been burned down in several villages,” he said, adding that 12 people were also seriously injured.
Hema herders and Lendu farmers have been locked in violence in Ituri for decades, with tens of thousands killed from 1999 to 2003.
A high-ranking provincial official, who did not wish to be named, confirmed the death toll since Friday and said 10 Lendu fighters also died.
“Four people (from the Hema community) died this morning. A police captain died from gunshot wounds and three police were injured,” the official said.
“Between 500 and 800 families have been displaced,” he added.
Ituri is part of DRC’s deeply troubled eastern region that includes the restive North and South Kivu provinces, where militias hold sway over huge areas.
In 2003, the violence was so great it triggered Operation Artemis, a three-month operation by the European Union, its first military mission outside Europe.
It succeeded in the goal of avoiding a humanitarian catastrophe, but the fighting never came to a total halt, and occasional flare-ups still wrack the area.
On Monday, the Catholic charity Caritas said more than 30 people had been killed in the Djugu area and blamed the new clashes on “Lendu combatants.”
“They come naked and in silence. They burn down huts, take away possessions and kill people they see or who resist them,” Caritas said.
It called on the Congolese government to protect civilians and property and arrest those responsible.
The UN peacekeeping mission in DRC, MONUSCO, said it would conduct an air reconnaissance mission to assess the situation.
The Hema community has begun two days of mourning and stopped all commercial activity as a mark of respect.
The latest violence comes amid uncertainty over the future of President Joseph Kabila, who has ruled since 2001.
Kabila, whose regime has been widely criticised for corruption and repression, was meant to finish his second and final term in office more than a year ago, but has stayed in power.
Under a deal brokered by the Catholic Church, he was meant to step down under elections that should have been held last year. Instead, the polls have been postponed until December this year.
The opposition have accused Kabila of seeking to remain in power as long as possible.
“We are approaching the elections and there are hotbeds of tension all over the country, Kasai, in the Kivus and now there is renewed violence in Ituri. We must remain on our guard,” said opposition MP Juvenal Munubo.
Ituri has remained a “breeding ground for violence, because there has been no real reconciliation between Lendu and Hema,” he added.