The Rwanda-backed M23, considered a "terrorist movement" by Kinshasa, has seized vast swathes of territory in east DRC since its resurgence in 2021.

The area, which is rich in natural resources, has been plagued by different conflicts for 30 years.

The M23 armed group has gained ground in recent weeks and earlier this month took control of Masisi, the administrative capital of the Masisi territory in North Kivu province.

The Congolese army has said it is "determined" to retake lost territories and has been conducting counter-offensives for several days, with the situation remaining confused in several areas.

Around 20 kilometres (12 miles) from the North Kivu provincial capital, Goma, fighting was taking place on Wednesday around the localities of Nyiragongo and Kibumba.

Some 70 kilometres from the provincial capital, in the Ngungu locality, intense fighting has been underway for several days, according to local sources and residents.

The fighting has caused a massive new wave of displacement, with the UN reporting last week that more than 100,000 people had fled their homes.

Nearly 2,500 people arrived at the Bulengo displaced persons camp near Goma in recent days, official Mahoro Faustin told AFP.

They were installed in hangars in the camp, where around 38,500 families were already crammed.

At Masisi hospital and MSF bases up to 10,000 people, including many families with children, have come to seek refuge, according to the medical charity.

Several dozen people who had been wounded, mostly civilians hit by bullets or shrapnel, have been treated since the beginning of January.

The International Committee of the Red Cross (ICRC) treated more than 130 injured people at Goma hospital in the same period.

"The number of injured civilians is worrying and the ICRC fears that the situation will deteriorate in the coming days," ICRC spokesperson Reagan Kambale told AFP.