The attack happened in North Kivu province where several armed groups are fighting for control of the mineral rich area, Africa News reported.
The UN peacekeeping mission in Congo is the largest in the world and is aimed at calming a number of armed groups in the vast, mineral-rich Central African nation.
The radio station, citing military sources, said fighting had lasted four hours.
UN Secretary-General Antonio Guterres described it as the worst attack on UN peacekeepers in recent history.
“It’s a very huge attack, certainly the worst in recent memory,” UN deputy-spokesman Farhan Haq said.
The Democratic Republic of the Congo had one of the most brutal colonial rules before undergoing decades of corrupt dictatorship and back-to-back civil wars that left the mineral-rich country poor and politically unstable.