An attack by militiamen has killed 45 people, and wounded a dozen more in Ituri province in eastern DR Congo, the United Nations mission in the country (MONUSCO) says.

According to MONUSCO, the attack on a camp for displaced people located 75 kilometres from Bunia in Djugu territory happened on the night of Sunday June 11 to 12.

"This targeted massacre against vulnerable displaced persons is attributed, according to our information, to the militiamen of the Coopérative pour le Développement du Congo (CODECO)," the UN mission said in a statement on Monday.

"MONUSCO urges the Congolese authorities to conduct an investigation and bring to justice the perpetrators of these summary executions."

The UN mission said the attack "constitutes a serious violation of the international humanitarian law," warned militias that similar attacks could amount to war crimes.

The CODECO attack follows another carried out by suspected ADF militiamen last week in which at least 12 people were killed in Beni territory of North Kivu province. The ADF, an Islamist group from Uganda and one of the most notorious militias, has operated in Ituri and North Kivu since the late 1990s.

There are at least 70,000 displaced people in Djugu, according to the UN's Office for the Coordination of Humanitarian Affairs (UNOCHA).

The UNOCHA says at least 32 civilians were killed between May 15 and 19 in different territories of Ituri. In the first two weeks of April, the UNOCHA said, up to 150 civilians were killed by various armed groups in Ituri.

Ravaged by violence for nearly three decades, eastern DR Congo is home to nearly 120 local and foreign armed groups responsible for various human rights abuses and atrocities.

Multiple international and regional interventions are yet to restore normalcy in the restive region of eastern DR Congo.