Heavy gunfire resonated across the key eastern Congolese city of Goma on Sunday from the frontline just a few kilometres away.

Congo has severed diplomatic ties with Rwanda as fighting between Rwanda-backed rebels and government forces rages around the key eastern city of Goma, leaving at least 13 peacekeepers and foreign soldiers dead and displacing thousands of civilians.

Footage shows troops, some in army uniform, handing over arms to Rwandan security officers after crossing into eastern neighboring country at the main border crossing in Rwanda's Rubavu district - Ana

Rebels claim to have captured the key city of Goma in the DRC, as the decades-long conflict becomes even more volatile. Sky News takes a look at what's going on.

Congolese M23 rebels entered the centre of the eastern city of Goma on Monday, two witnesses said, hours after they claimed to have seized the city despite the United Nations Security Council demanding an end to the offensive.

The M23 armed group and Rwandan soldiers entered the centre of Goma on Sunday night after weeks of advancing on the main city in the Democratic Republic of Congo’s North Kivu province.

Fighting has escalated sharply in recent weeks in eastern Congo, where rebels have seized key towns and are closing in on the city of Goma, the government’s last stronghold in the North Kivu province,

The Democratic Republic of Congo (DRC) has severed diplomatic ties with Rwanda, accusing it of fuelling the rebellion. At least 13 soldiers serving with peacekeeping forces in the DRC have been killed in clashes with M23 rebels,

M23 rebels in the Democratic Republic of Congo were reported to have taken the key eastern city of Goma in fierce fighting with government forces that sent streams of refugees fleeing area communities.

Residents in eastern Congo’s largest city of Goma are fleeing after Rwanda-backed rebels claimed to have captured the regional hub from Congolese forces.

The M23 militia, funded and directed by Rwanda, said it had seized the city of Goma, terrifying its people, many of whom sought shelter there after fleeing the rebel advance.