The troops came across the corpses on Thursday by the Ituri river, in the Irumu territory of Ituri province, according to Red Cross representative David Beiza.
A Red Cross team later visited the area with soldiers and found the bodies, said Beiza, adding he suspected rebels from the Allied Democratic Forces (ADF) were responsible for the beheadings.
AFP was also unable to independently verify the information.
Dieudonne Malangay, a resident of the area where the bodies were discovered, also said there were 17 headless corpses.
“It is difficult to identify the victims because the bodies are decomposing,” he said, adding that they were likely killed by the ADF.
Described by the so-called Islamic State as its local affiliate, the ADF has been accused of killing thousands of civilians in DRC’s troubled east.
Experts suggested the militia was responsible for a May 11 attack in Irumu territory that left at least 20 civilians dead.
More than 120 armed groups roam eastern DRC and civilian massacres are common.
Congolese security forces have governed Ituri province and neighbouring North Kivu since May last year, in a bid to crush the deadly militias. But conflict has continued.
Two local officials told AFP that fighters from the CODECO — another feared militia — killed nine civilians on Thursday further north in Ituri.
