Fighters from the M23 rebel group seized the town of Kiwandja in eastern Congo on Saturday, residents and a local official said, effectively cutting North Kivu's capital Goma off from the upper half of the province as the United Nations peacekeeping mission in the country announced an increase in its "troop alert level" following deadly clashes with rebels in the east.

The MONUSCO mission condemned "the hostile acts of M23" rebel group and called for an immediate halt to the fighting.

It was providing "air support, intelligence and equipment" as well as medical assistance to the DRC's army, the mission said on Twitter.

The peacekeepers said they were "mobilized in support" of the FARDC army which clashed this week with the M23 around a strategic highway, with residents reporting at least 10 people dead since Sunday and dozens more injured.

MONUSCO said it had set up an "operations coordination center" with the army and was carrying out reconnaissance and surveillance flights, but did not provide further details about the alert level.

Several witnesses told Agence France-Presse (AFP) by telephone on Saturday that the M23 had seized control of Kiwanja and Rutshuru-centre, along the RN2 highway linking the North Kivu provincial capital Goma with the north and Uganda.

M23, a mostly Congolese Tutsi group, resumed fighting in late 2021 after lying dormant for years.

It has since captured swathes of territory in North Kivu province, including the strategic town of Bunagana on the Ugandan border in June.

The group's resurgence has destabilized regional relations in central Africa, with the DRC accusing its smaller neighbor Rwanda of backing the militia.

The rebel group first leapt to prominence in 2012 when it briefly captured Goma before a joint Congolese-U.N. offensive drove it out.

The militia is one of scores of armed groups that roam eastern DRC, many of them a legacy of two regional wars that flared late last century.