An armed group has attacked a base of the United Nations peacekeepers in the east of the Democratic Republic of the Congo, killing at least 14 peacekeepers and wounding 40 others.
The UN peacekeepers, who were mostly from Tanzania with at least five Congolese soldiers, blamed the Friday attack on a rebel group based in neighboring Uganda.
"It's a very huge attack, certainly the worst in recent memory," said UN deputy-spokesman Farhan Haq from New York.
The base, which is located about 45 kilometers from the town of Beni, has been repeatedly attacked by rebels from the Allied Democratic Forces (ADF) rebel group. It is home to the peacekeeping mission's rapid intervention force, which has a rare mandate to go on the offensive, according to Radio Okapi, which is backed by the UN mission.
The UN has described the attack in Congo as the worst in the recent UN history as well as a war crime.
The radio station, citing military sources, said fighting had lasted four hours.
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.
In 2006, the UN mission helped carry out Congo's first free and fair elections in 46 years, paving the way for President Joseph Kabila to be elected for a five-year term.
His second term in office ended in 2016. Under the DR Congo's constitution, Kabila is banned from seeking a third term. However, Kabila is authorized to stay in office until his successor is elected but he decided to remain in power. This prompted the UN to urge the Congolese authorities "to respect the fundamental freedoms enshrined in the Congolese Constitution."
The delay in holding an election has flared up violence in the country.