By Yassin Kombi and David Lewis GOMA, Democratic Republic of Congo (Reuters) -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,

A rebel alliance claimed the capture of the biggest city in the Democratic Republic of Congo’s mineral-rich eastern region this week, pushing back against resistance from government troops backed by regional and UN intervention forces.

The weeks-long march of the M23 armed group, which has captured vast swathes of eastern DRC including most of the key city of Goma, has prompted calls for crisis talks and warnings of a looming humanitarian crisis.

U.S. Secretary of State Marco Rubio called for a urgent cease-fire in the conflict in eastern Democratic Republic of Congo saying Washington was "deeply troubled" by a recent escalation in the fighting.

Rwanda, which diplomats say backs M23 fighters who seized Goma in Democratic Republic of Congo this week, called on Wednesday for a ceasefire across eastern Congo and for Congo to negotiate with the rebels while denying Rwandan troops were involved.

Democratic Republic of Congo's M23 rebels are moving south towards Bukavu, the capital of South Kivu province, in what appears to be an attempt to expand their area of control in the country's east after capturing the city of Goma.

Democratic Republic of Congo's M23 rebels are moving south towards Bukavu, the capital of South Kivu province, in what appears to be an attempt to expand their area of control in the country's east after capturing the city of Goma.

Democratic Republic of Congo's M23 rebels are moving south towards Bukavu, the capital of South Kivu province, in what appears to be an attempt to expand

Congo government forces were nowhere to be seen as the M23 rebels in Democratic Republic of Congo were moving south on Wednesday towards Bukavu, the capital of South Kivu province

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.

M23 rebels captured the key city of Goma in the eastern DRC Monday, forcing thousands of civilians to flee in the latest in a series of advances - Anadolu Ajansı