The FARDC regular army took back control of both the city of Rutshuru and the rebel-held town of Kiwanja, home to a base used by the UN mission MONUSCO that had been repeatedly looted by rebels, said the governor of North-Kivu province, Julien Paluku.
MONUSCO said a Tanzanian officer was killed in Kiwanja, where United Nations forces joined the army to drive out rebels on the third day of clashes since a fresh flare-up in violence on Friday. The circumstances of his death were unclear, said the UN force.
"The soldier died while protecting the people of Kiwanja," said MONUSCO head Martin Kobler in a statement.
The spokesperson for UN Secretary-General Ban Ki-moon said in a statement the UN chief "condemns in the strongest terms the killing of a Tanzanian peacekeeper who came under fire from the M23 movement in eastern Democratic Republic of the Congo.
Also Read
"The Secretary-General offers his sincere condolences and sympathy to the family of the victim, and to the Government of the United Republic of Tanzania."
The statement added that the United Nations "remains committed to taking all necessary actions to protect civilians in eastern Democratic Republic of the Congo".
M23 said it had "retreated without combat", saying it "refused to fight in Kiwanja".
In a statement, the group also threatened to pull out of stalled peace talks with Kinshasa unless there was an "immediate cessation of the hostilities".
In the town of Rutshuru, relieved residents "showered soldiers with flowers to thank them for their help" after the rebels fled, according to one local man who gave his name as Bruno.
By last evening, a high-ranking army officer said troops had also taken the strategic town of Kibumba, which has seen heavy fighting since clashes first broke out there on Friday. "Kibumba is under FARDC control," the source told AFP.