Congolese authorities have blocked access to the airport in Goma, a provincial capital in eastern Democratic Republic of Congo, and cancelled flights as rebels advance on the city, three officials told Reuters on Sunday.

Congo has severed diplomatic ties with Rwanda as fighting between Rwanda-backed rebels and government forces rages around the key eastern city of Goma.

Fighting with M23 rebels in eastern Democratic Republic of Congo left six United Nations peacekeepers dead, UN officials said Saturday.

Congolese authorities have blocked access to the airport in Goma, a provincial capital in eastern Democratic Republic of Congo, and cancelled flights as Rwandan-backed rebels advance on the city, three officials told Reuters on Sunday.

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,

Armed rebels in the Democratic Republic of Congo have closed in on Goma, a major city in the country. This comes as thousands have fled their homes to escape the violence. NBC News' Kier Simmons has more on the invasion.

GOMA, Democratic Republic of Congo (Reuters) -Rwandan-backed M23 rebels laying siege to eastern Congo's largest city Goma ordered defending government forces late on Sunday to disarm and surrender, saying they were preparing to enter and take control.

Rebels in Democratic Republic of Congo are closing in on a key city in the mineral-rich region aided by neighboring Rwanda’s army, the head of a peacekeeping mission told United Nations Security Council members during an emergency meeting on Sunday.