The capital of one of the Democratic Republic of Congo’s most mineral-rich regions is being “asphyxiated” as armed rebels close in on the city in a conflict that threatens to explode into a wider regional war, aid agencies and analysts have warned.

As fighting between M23 rebels and DRC government forces intensified around Goma, capital of the eastern province of North Kivu, the situation had become “really catastrophic”, said Angèle Dikongué-Atangana, DRC country representative for UNHCR, the UN refugee agency.

M23, which observers say is being backed by neighbouring Rwanda, has fought its way to within 25km of Goma. The rebel group controls almost all supply routes into the city, where the 1.5mn-strong population has been swelled by hundreds of thousands of displaced people, sending the price of basic commodities rocketing, according to aid agencies and analysts.