Congolese President Félix Tshisekedi has vowed to restore government authority in the east, where Rwanda-backed M23 rebels have seized much of the city of Goma and are reportedly advancing south to seize more territory.

Rwanda-backed fighters advanced on a second front in their lightning offensive across eastern DR Congo on Wednesday after seizing control of most of the key city of Goma during heavy fighting with the Congolese military.

(Reuters) - 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.

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.

By Yassin Kombi and Sonia Rolley GOMA, Democratic Republic of Congo (Reuters) - Rwanda's President Paul Kagame said he agreed with the U.S. government on the need for a ceasefire in eastern Congo but gave no indication of bowing to calls for Rwandan troops and the M23 rebels they support to withdraw from Goma.