The Rwanda-backed M23 armed group were threatening another key town in eastern Democratic Republic of Congo (DRC) on Friday as the United Nations warned the risk of violence spreading regionally had "never been higher".

M23 and Rwandan troops seized the city of Goma last week and are now pushing into the neighbouring South Kivu province.

Thousands have died and huge numbers displaced as they have overtaken swathes of the mineral-rich region, routing DRC troops and their allies in the latest episode of decades-long turmoil in eastern DRC.

Rwandan President Paul Kagame and DRC President Felix Tshisekedi are due to attend a summit in Tanzania on Saturday as regional powers try to defuse the crisis.

The UN Human Rights Council met in Geneva on Friday to decide on launching an international investigation into alleged abuses committed in the conflict.

UN rights chief Volker Turk warned that "the risk of violence escalating throughout the sub-region has never been higher".

"If nothing is done, the worst may be yet to come, for the people of the eastern DRC, but also beyond the country's borders," he said.

Turk said that nearly 3,000 people had been killed and 2,880 injured since M23 entered Goma on January 26, adding that the real figures were likely much higher.

Also on Friday, a Swiss NGO said three local staff were killed in the area this week.

Assault on Kavumu

Humanitarian and local sources said Thursday that Congolese forces were bracing for an assault on the town of Kavumu, which hosts an airport critical to supplying DRC forces.

Equipment and troops were being evacuated to avoid being captured by the advancing M23 and its Rwandan allies, the sources said.

Kavumu is the last barrier before the South Kivu provincial capital Bukavu, some 30 km away.

In Goma, where the M23 has already installed its own mayor and authorities, the group convened tens of thousands of people on Thursday for a public meeting of the River Congo Alliance, a political-military coalition that includes the M23.

The head of the alliance, Corneille Nangaa, told the crowd that the group wants to "liberate all of the Congo".

Young people at the meeting in the city's packed stadium chanted "Go to Kinshasa!", the DRC's capital on the other side of the vast country, which is roughly the size of Western Europe.

The DRC issued an international arrest warrant for Nangaa on Wednesday.

Since the M23 resurfaced in late 2021, the DRC army, which has a reputation for poor training and corruption, has been forced into multiple retreats.

The lightning offensive has raised fears of regional war, given that several countries are engaged in supporting DRC militarily, including South Africa, Burundi and Malawi.

Previous peace talks hosted by Angola and Kenya have failed.

The latest peace effort in Tanzania brings together the eight-country East African Community and 16-member Southern African Development Community.

It was set to start with a ministerial meeting on Friday, before the arrival of Kagame, Tshisekedi and other regional leaders on Saturday.

A UN expert report said last year that Rwanda has "de facto" control over the M23, alongside some 4,000 of its own troops in the conflict zone.

The report also accused Kigali of profiting from smuggling out minerals from the DRC - particularly coltan used in phones and laptops, as well as gold.

Rwanda denies direct involvement and accuses the DRC of sheltering the FDLR, an armed group created by ethnic Hutus who massacred Tutsis during the 1994 Rwandan genocide.

AFP