Armed men launched their assault on towns of Oicha and Kisima in North Kivu Province with killings in Congo’s mineral-rich east said to have more than doubled in last year.
Thirteen people have died in attacks in the eastern Democratic Republic of Congo region of Beni, local officials and experts have said, blaming a notorious militia called the Allied Democratic Forces (ADF).
ADF men attacked the village of Kisima late on Tuesday, "leaving 11 dead," said Bozi Sindiwako, the chief official for the Rwenzori area in North Kivu province.
That toll was confirmed by US-based monitoring group, the Kivu Security Tracker (KST).
The army also said there was an attack, without giving the number of casualties.
"Clean-up operations continue in the area," Beni army spokesperson Antony Mwalushay said.
In a separate attack overnight, two people, a civilian and a soldier, were killed in the North Kivu city of Oicha, its mayor Nicolas Kikuku said. He added that an ADF fighter was also killed.
The new deaths bring the number of civilians killed by armed groups in Beni since November 2019 to at least 1,013, KST told AFP.
In late 2019 the Congo army began a campaign to eliminate the ADF, which originated as an Ugandan militia that has been operating in the vast country since the 1990s.
The ADF responded with a series of retaliatory massacres of civilians.
"We have just launched a new operation in the Rwenzori sector in a bid to drive the ADF enemy out of the Congolese territory," army spokesperson Antony Mwalushayi said. "The problem is that we have an enemy that attacks the defenceless."
The Congo, a central African country the size of continental western Europe, has been plagued by militia violence in its east for more than a quarter of a century.
In a report published on Monday, KST said 122 armed groups are active in the country's four eastern provinces, North and South Kivu as well as Ituri and Tanganyika.
The most notorious group in North Kivu is the ADF, whose stronghold lies in the Beni area, near the Ugandan border.
The ADF settled in the DRC in 1995 and in recent years they have given up on attacks in neighbouring Uganda.
The military offensive has scattered the group, which now operates in small, mobile groups, according to a recent report by UN experts.
After a brief lull in activity, ADF attacks have been ramping up since the start of February.
"We are farmers but they don't want us to even have access to our fields, that's killing us twice. They've also burned down several houses and taken some of the inhabitants into the bush," activist Roger Masimango said.
"They killed my father and my brothers," said Kavuva Blaise, who witnessed the attack on Kisima. "I was saved by a miracle. They were so numerous and spoke in a foreign language, that is what made me believe that it was really the ADF."
Daesh has claimed responsibility for several suspected ADF attacks in the past, but UN experts in the region have found no direct link between the two groups.