Rwandan-backed rebels are gaining ground in eastern Congo despite the unilateral ceasefire they declared earlier this week.

The M23 rebels took control of a town 100 kilometres (60 miles) from the provincial capital of Bukavu despite a ceasefire.

Rebels occupying the eastern Democratic Republic of Congo city of Goma have declared a cease-fire but the government dismissed the pause in the fighting as a ruse aimed to head off growing international concern.

The Rwanda-backed rebels who seized eastern Congo's key city of Goma announced Monday a unilateral ceasefire in the region for humanitarian reasons, following calls for a safe corridor for aid and hundreds of thousands of displaced people.

Over 2,000 bodies require burial in Goma after Rwanda-backed M23 rebels took over the Democratic of Congo city last week, inflaming a decade-old conflict and humanitarian crisis, Congo's communications minister Patrick Muyaya said late on Monday.

Rwandan-backed M23 rebels have seized control of the town of Nyabibwe in eastern Democratic Republic of Congo's South Kivu province, eight sources said on Wednesday - an apparent violation of a unilateral ceasefire they declared this week.