The UN on Tuesday said the humanitarian situation in the besieged DR Congo city of Goma was "extremely worrying" amid mass displacement, food shortages, looted aid, overflowing hospitals and widespread sexual violence.

There are growing international calls for peace talks to end the escalation of violence in the east of the Democratic Republic of Congo. The fate of the economic and trading hub Goma is still unclear. UN officials have said the situation is chaotic with fighting continuing in parts of the city.

Bodies are lying on the streets. Medical staff in overwhelmed hospitals are treating hundreds of wounded civilians against the backdrop of gunfire and mortar fire.

Speaking to BBC Newshour while being locked down in a UN bunker in the city, the deputy head of the UN force, Vivian van de Perre, said the M23 rebels had "established" themselves in Goma, but were still facing "pockets of resistance".

Thousands fled the city of Goma on Monday as fighting raged between Congolese forces and rebels backed by neighboring Rwanda, who claimed to have captured eastern Congo’s largest regional hub.

"Active zones of combat have spread to all quarters of the city, all the neighborhoods of the city," Lemarquis, the deputy U.N. envoy and top U.N. aid official in the DRC, told reporters in New York via video from Kinshasa.

Fighting with M23 rebels in eastern Democratic Republic of Congo left six United Nations peacekeepers dead, UN officials said Saturday.

A day after the rebels marched into the lakeside city, protesters in the capital attacked a UN compound and embassies including those of Rwanda, France and the United States, expressing anger at what

Unidentified people in civilian clothing enter UN base in Goma, hand over weapons to the Uruguayan Blue Helmets that are part of the MUNESCO peacekeeping force. Video credit: Social media.

A rebel alliance spearheaded by the ethnic Tutsi-led M23 militia said it had seized the lakeside city of more than 2 million people.

In June last year, Rwanda's government spokesperson Yolande Makolo hit out about the presence of mercenaries in eastern DR Congo, saying it was a violation of the Geneva Conventions, which prohibit the use of hired combatants. In response, Congolese government spokesperson Patrick Muyaya dismissed what he called Rwanda's perennial complaint.