Nearly 3,000 people were killed over the last week as rebels captured a key city in one of the deadliest battles in the Central African country in decades.

The Democratic Republic of Congo will present a motion to the United Nations Human Rights Council seeking an investigation into what it called "mass violations" of rights in the city of Goma, its envoy told reporters on Thursday.

Rwanda-backed rebels gained ground in eastern Congo on Wednesday despite the unilateral ceasefire they declared earlier this week, taking control of a town 60 miles from the provincial capital of Bukavu,