The Islamic State group has issued a statement claiming responsibility for killing more than 35 people and wounding dozens in eastern Congo.

In the statement, posted Friday by Aamaq, the militants' news agency, it said it killed “Christians” with guns and knives and destroyed their property in Mukondi village in North Kivu province. It also published a photo of the houses on fire.

The announcement comes after local authorities confirmed that at least 45 people were killed last week in several attacks on different villages by rebels from the Allied Democratic Forces, a militia with links to IS.

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Conflict has been simmering in eastern Congo for decades as more than 120 armed groups fight for power, influence and resources, and some to protect their communities. The ADF has been largely active in North Kivu province but has recently extended its operations into neighboring Ituri province and to areas near the regional capital, Goma.

Efforts to stem the violence against ADF have yielded little. A nearly year-long joint operation by Uganda and Congo’s armies did not achieve the expected results of defeating or substantially weakening the group, said a report in December by a panel of U.N. experts. The ADF rebels are accused by the U.N. and rights groups of maiming, raping and abducting civilians, including children. Earlier this month the United States offered a reward of up to $5 million for information that could lead to the capture of the group’s leader, Seka Musa Baluku.

On Thursday, AP reporters saw bodies lowered into a mass grave in Mukondi. Community members shoveled dirt over the bodies against a backdrop of destroyed houses and said the government wasn't doing enough to protect them.

“As you see in Mukondi, it is always the same. ADF, which is always ill-intentioned against the Congolese," said Col. Charles Ehuta Omeonga, military administrator for Beni region. “We lost many of our brothers,” he said.

The United Nations peacekeeping mission in Congo has condemned the killings and is urging Congo’s authorities to investigate and bring those responsible to justice.