Fighting across the largest city in eastern Democratic Republic of Congo and "is still very much ongoing ... it's not over yet," senior U.N. official in Congo, Bruno Lemarquis, said on Monday after Rwandan-backed M23 rebels claimed to have control of Goma.

In the aftermath of its withdrawal from Goma, the M23 suffered a series of heavy defeats at the hands of the Congolese army, which was backed by a multinational force. The M23 were subsequently expelled from the country. M23 fighters then agreed to be re-integrated into the army in return for promises that Tutsis would be protected.

The United Nations Security Council, Secretary-General Antonio Guterres and senior U.N. officials are calling for the M23 to immediately cease hostilities and withdraw from occupied territories. They have called for the withdrawal of Rwandan forces and a return to the Luanda process of mediation overseen by Angolan President Joao Lourenco.