Terrified residents in Lubero, some 250 kilometres (155 miles) north of the provincial capital Goma, told to AFP that mobs of Congolese soldiers were looting as M23 advanced on the town.

"I ask all the soldiers who deserted the front and are hanging around in Lubero and its surroundings to return to their commanders," Colonel Mak Hazukay, a spokesperson for the army in the region, said in a message broadcast on local radio stations.

"A soldier must not abandon his superior and his group."

A journalist in Lubero, who asked to remain anonymous because of security concerns, told AFP that "fleeing soldiers had opened fire in the centre" and "looted shops and stores".

Several residents contacted by AFP confirmed the account.

Aline Nyota said she was travelling from Lubero to Butembo, 45 kilometres further north, when "the Congolese soldiers we met robbed us: phones, money and other goods".

"If you hesitate, they shoot," she said.

The local journalist said Ugandan troops backed by tanks were patrolling Lubero to provide security.

M23 forces, backed by Rwandan troops according to the United Nations, have faced little resistance since taking Goma on January 28.

"It up to us to show resistance, to rejoin our positions and work," said Colonel Hazukay, pleading with deserters not to mistreat civilians.