Officials and residents say Rwanda-backed rebels have gained ground in eastern Congo despite the unilateral ceasefire they declared earlier this week, taking control of a town 100 kilometers (60 miles) from the provincial capital of Bukavu.

DR Congo requested the urgent meeting of the UN's top rights body to discuss escalating fighting by Rwanda-backed armed group M23 in North and South Kivu provinces, and drew up a draft resolution that would set up the probe.

A conflict that has raged for decades reached a flashpoint this week when rebels backed by Rwanda marched on a key Congolese city in a bid to occupy territory and exploit minerals.