A senior regional official in the eastern Ituri province said "attackers armed with guns and knives killed 21 civilians in Mahagi," which was the deadliest attack in three days.
Forty-three people have died in three days of clashes between armed groups and soldiers in Democratic Republic of Congo's (DRC) perennially unstable east, government and army officials told AFP on Monday.
The deadliest clash occurred on Friday when "attackers armed with guns and knives killed 21 civilians in Mahagi," said Gilbert Tsale, a senior regional official in the eastern Ituri province.
In the neighbouring Djugu area, fighting has raged since Sunday in Lisey, pitting the army against militias, Colonel James Ngongo, the army spokesman in Ituri said.
"Two soldiers died, the attackers killed two civilians while fleeing and the army killed 12 assailants," he said.
On Sunday, an attack by the Armed Democratic Force (ADF) militia claimed the lives of five men and one woman, John Kambale, the local head of Malambo, near the eastern town of Beni in North Kivu province said.
The ADF movement originated in neighbouring Uganda, opposed to the rule of President Yoweri Museveni, but swiftly moved in 1995 into the DRC, which became its base of operations.
ADF fighters are accused of killing more than 1,000 civilians in the Beni region since October 2014.
Its members stepped up massacres last November in reprisal for the military offensive, at a cost of almost 400 lives, according to experts.
The rebels have carried out no attacks inside Uganda for years.
A UN report in January said more than 700 civilians had been killed in Ituri since the end of 2017.