Congo's leader has called on young people to enlist in the army to help fight Rwanda-backed rebels attempting to seize more territory in the country's conflict-battered east.

As an East African bloc urged an immediate ceasefire in eastern Democratic Republic of Congo, Rwandan-backed M23 rebels who seized the city of Goma extended their advance on Wednesday, and Congo said it planned a campaign to recover lost territory.

Regional tensions spiral as peacekeepers killed in fighting following Rwandan-backed M23 rebel group offensive

Local sources said Kigali-backed fighters were advancing on a new front and had seized two districts in South Kivu province, after the rebel group’s capture of most of Goma, the capital of North Kivu.

South African President Cyril Ramaphosa accuses Rwanda of backing M23 rebels behind escalating crisis in eastern Democratic Republic of Congo this week

Many Congolese see the rebel advance as an invasion of their country by a foreign power in an attempt to seize land and Congo’s valuable rare minerals.

M23 rebels, with support from Rwandan troops, marched into Goma earlier this week and are now advancing south toward Bukavu.

The group's capture of most of Goma, the capital of North Kivu province, is a dramatic escalation in a region that has seen decades of conflict involving multiple armed groups.

Reuters quoted the spokesperson as saying that the UN is deeply concerned by these developments, which are backed by "credible reports."

Democratic Republic of Congo President Felix Tshisekedi has vowed “a vigorous and coordinated response” against a rebel alliance that has besieged swaths of the nation’s mineral-rich east and forced hundreds of local troops and foreign mercenaries to surrender.

UN Secretary-General Antonio Guterres on Tuesday talked over the phone with the presidents of the Democratic Republic of the Congo (DRC)