Residents of the besieged city of Goma, in the east of the Democratic Republic of Congo, say they are gripped by fear as gunshots continue to ring out around their homes, days after rebel forces claimed they had taken over.

The Rwandan-backed M23 rebels have released captured Romanian mercenaries who were fighting with the Congolese army. As they passed a border, they were chastised by Willy Ngoma, who tapped them mockingly one by one.

Rebels appear to be edging closer to taking control of the key city of Goma in the east of the Democratic Republic of Congo following reports that they had captured its airport. The Congolese government has insisted that it is still in charge as fighting in parts of the city continues.

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.

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.