As an East African bloc urged an immediate ceasefire in eastern Democratic Republic of Congo, Rwandan-backed M23 rebels who seized the city of Goma extended their advance on Wednesday, and Congo said it planned a campaign to recover lost territory.

Rwanda denies sending troops into neighbouring Democratic Republic of Congo, where U.N. investigators said in December thousands of Rwandan soldiers had been deployed in support of the M23 rebel group. The rebels took control of the city of Goma in the volatile, mineral-rich east on Tuesday.

M23 rebels in the Democratic Republic of Congo were reported to have taken the key eastern city of Goma in fierce fighting with government forces that sent streams of refugees fleeing area communities.