More than 70 people have been massacred in eastern Congo, with many of the victims hacked to death with machetes in the Masisi territory.
The UN said in a statement on Friday that the men and women were summarily executed.
A peacekeeping mission team is now on the ground to verify the allegations.
In New York, spokesman Martin Nesirky said the UN mission in the country (MONUSCO) is concerned by the reports of the massacre.
"The reports received by MONUSCO suggest that the summary executions were allegedly committed mainly by armed groups to spread terror among the population," MONUSCO said in a statement.
"The majority of the victims were killed with machete.
The killings happened in late January and early February, a MONUSCO spokesman told AFP.
They took place in the Nyamaboko villages I and II in the resource-rich northeastern North Kivu province where armed groups regularly attack civilians over ethnic or commercial disputes.
In December, MONUSCO's intervention force, whose mission is to neutralise all the armed groups active in the troubled country, boosted its presence in the area.
Masisi, a mineral-rich area of North Kivu province in eastern Congo, has been in the crosshairs of Congo's conflict for years.
Government troops struck a rare and striking military success when, backed by the UN brigade, they defeated the powerful M23 rebel group in November.
Since then, MONUSCO has been focusing on going after other armed militias operating in the same region.
