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

Rwanda-backed rebels say they captured eastern Congo’s strategic city of Goma, the hub of a region containing trillions of dollars in mineral wealth that remains largely untapped.

Nine United Nations peacekeepers in eastern Congo sustained injuries during fighting with the M23 armed group, the U.N. said, as the rebels close in on Goma.

Congo’s M23 rebels say they have taken control of the key eastern city of Goma.

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.