A new attack on the Ivo displaced people's camp in the northeast of the Democratic Republic of Congo on Sunday claimed the lives of 22 civilians, an aid worker said.
The same camp was attacked less than a week ago when 29 people were killed.
He accused the armed group Cooperative for the Development of Congo (CODECO) of carrying out the attack.
The Kivu Security Tracker (KST), a respected US-based monitor of violence in the region, cited the same death toll.
The army spokesman in the region, Lieutenant Jules Ngongo, said the CODECO rebels were repelled, but did not elaborate.
EU foreign policy chief Josep Borrell Fontelles called for strong action against the perpetrators.
"The EU condemns the new appalling attacks committed by the militia against civilian populations, particularly the internally displaced persons," he wrote on Twitter.
Gold-rich Ituri province has been plunged back into a cycle of violence since late 2017 with the rise of the CODECO militia, which has since split into rival factions.
Ituri and neighbouring North Kivu have been under a state of siege since May 6, an exceptional measure to combat armed groups including CODECO and the Allied Democratic Forces (ADF).
Civilian authorities have been replaced by military and police officers.
Two other attacks took place overnight Saturday elsewhere in Ituri, leaving a total of nine civilians dead, civil society leader Isaac Nyakuklinda told AFP.