Over 100,000 people have been displaced in the past week due to recent fighting in eastern Democratic Republic of Congo, the United Nations humanitarian office reported Tuesday.

Rwanda-backed M23 rebels seized control of Masisi on Saturday, a key town in the mineral-rich DRC.

"Between Jan. 1 and 3, 2025, intense clashes between the Congolese army and a non-state armed group in Masisi Centre, North Kivu province, displaced an estimated 102,000 people, according to local reports," the U.N. Office for the Coordination of Humanitarian Affairs said.

Rwanda's Foreign Ministry claimed that the areas taken by M23 forces in recent days had been in the hands of Hutu militias linked to the 1994 mass killings of Tutsis in Rwanda.

"Many parts of Masisi territory are/were in the hands of the genocidal FDLR, which is a foreign force that is occupying a Congolese territory," Foreign Minister Olivier Nduhungirehe said in the statement.

He also denounced international criticism that had not condemned "the continued violation of the integrity of Congolese land belonging to Congolese communities, including Tutsi Congolese."

Masisi, with a population of around 40,000 people, is about 80 kilometers (50 miles) north of North Kivu's provincial capital Goma.

Relative calm returned to Masisi by Jan. 5, prompting some displaced families to begin returning, OCHA said.

"Humanitarian actors warn the influx of displaced people may worsen Masisi's dire situation, with over 600,000 displaced as of 30 November 2024," the U.N. body added.

Between Friday and Monday, MSF and health ministry teams treated 75 people at two hospitals in the area, MSF said in a statement Tuesday.

"In addition to providing this care, these two health facilities also sheltered hundreds of civilians for several days, who sought refuge there to benefit from increased protection," said Stephane Goetghebuer, head of mission in charge of the medical charity's projects in North Kivu.

The March 23 Movement (M23), a militia supported by neighboring Rwanda and its army, has seized vast swathes of the east of the DRC since 2021, displacing thousands and triggering a humanitarian crisis.

Rwanda's statement blamed the ongoing fighting on "the marginalization of the Congolese Tutsi, victims of hate speech, discrimination and persecution."

Angola-mediated talks between DRC President Felix Tshisekedi and his Rwandan counterpart Paul Kagame were abruptly canceled in mid-December over disagreements on the terms of a proposed peace deal.

For 30 years, eastern DRC has been ravaged by fighting between local and foreign armed groups, dating back to the regional wars of the 1990s.