Rwanda-backed rebels who captured eastern Congo's largest city said on Thursday they want to take their fight to the far-off capital, Kinshasa, while Congo's president called for a massive military mobilization to resist the rebellion and his defence minister rejected calls for talks.

In a video message, Congo's Defence Minister Guy Kabombo Muadiamvita said he has directed plans for any dialogue with the rebels to "be completely burned immediately."

"We will stay here in Congo and fight. If we do not stay alive here, let's stay dead here," said Muadiamvita, a close ally of Congo's president.

At a briefing where they sought to assert their control over the eastern city of Goma and surrounding territory in the neighbouring South Kivu province, the M23 rebels said they would be open to dialogue with the government, which was also proposed by the east African regional bloc, of which Rwanda is a member.

Their motive, however, is to gain political power, said Corneille Nangaa, one of the political leaders of M23, during the briefing.

"We want to go to Kinshasa, take power and lead the country," Nangaa said. He did not indicate how the rebels planned to advance on the capital, more than 1,500 kilometres away.

Rwanda's leader, Paul Kagame, said he spoke with Angola's President Joao Lourenco — a mediator in the conflict who also met with Congo's leader a day earlier — and both leaders committed to working with other African countries to resolve the hostilities.

Congo's president vows 'vigorous, co-ordinated response'

A UN spokesman said the agency is "disturbed" by reports that neighbouring Rwandan forces have crossed the border in the direction where the rebels are said to be advancing.

The M23 rebels are backed by some 4,000 troops from Rwanda, according to UN experts, far more than in 2012, when they first captured Goma. They are one of more than 100 armed groups vying for control in Congo's mineral-rich east, which holds vast deposits estimated to be worth $24 trillion US and are critical to much of the world's technology.

Congolese President Félix Tshisekedi, meanwhile, called on young people to enlist in the military, as a crucial meeting of neighbours asked the Congolese government to talk with the rebels. Rwanda's leader also threatened to "deal" with any confrontation with South Africa, which has complained that fighting in eastern Congo has left South African peacekeepers dead.

WATCH | M23 rebels claim control of Goma in eastern Congo: 

Rwanda-backed rebels claim control of Goma in eastern Congo

Desperation, looting and bodies in the streets are being reported in Goma, after Rwanda-backed M23 rebels claimed to have captured the Congolese city. It's the latest move after years of fighting in the country's mineral-rich east.

In his first public remarks since the M23 rebels advanced into Goma on Monday, Tshisekedi vowed "a vigorous and co-ordinated response" from his forces to push back the rebels, while reaffirming his commitment to a peaceful resolution. 

On Thursday, he met with French Foreign Minister Jean-Noël Barrot in Kinshasa, the Congolese presidency said on X, noting that France has provided significant support to Congo in recent UN meetings on the issue.

"[Congo] expects a little more action in the face of this crisis," it added.

Dead bodies, looting in Goma

Goma remained largely without electricity and water on Thursday, as the bodies of several alleged government soldiers lay in the streets.

M23 rebels escorted some 2,000 government soldiers and police officers — who they said surrendered — to an undisclosed location, some of them singing anti-Tshisekedi songs.

Bruno Lemarquis, the UN's humanitarian co-ordinator in Congo, said basic services are largely paralyzed in Goma, a humanitarian hub that's critical for more than six million people displaced by the conflict.

"After several days of intense clashes, the city is now [faced] with massive humanitarian needs and severely impacted response capacities," said Lemarquis.

Footage from Goma showed residents carrying food items and goods looted from stores and warehouses in the city.

"This is something that is going to exacerbate a dangerous cycle of violence as desperate times call for desperate measures," said Cynthia Jones, the UN World Food Program emergency co-ordinator in eastern Congo, on Thursday.

After capturing much of Goma, the rebels were advancing toward South Kivu's provincial capital, Bukavu, causing fear and panic among residents, witnesses said Thursday.

Who are the M23 and what do they want?

The chaotic situation with the M23 has its roots in ethnic conflict, stretching back to the 1994 genocide in Rwanda, when 800,000 Tutsis and others were killed by Hutus and former militias. M23 says it is defending ethnic Tutsis in Congo.

Rwanda has claimed the Tutsis are being persecuted by Hutus and others involved in the genocide. Many Hutus fled into Congo after 1994.

Unlike in 2012 when the rebels seized Congo for days, observers say their withdrawal could be more difficult now. The rebels have been emboldened by Rwanda, which feels Congo is ignoring its interests in the region and failed to meet demands of previous peace agreements, according to Murithi Mutiga, program director for Africa at the Crisis Group, a think-tank. 

"Ultimately, this is a failure of African mediation, [because] the warning signs were always there. Kigali was adopting very bellicose rhetoric and the Congolese government was also adopting very, very aggressive rhetoric," Mutiga said.