Rebels in the Democratic Republic of Congo say they have seized a town in the eastern part of the country after the army fled their advance.

Representatives for the M23 rebel movement said they took over Rutshuru around midday Sunday without any fighting. The town lies on the main road north from the North Kivu provincial capital, Goma.

The rebels' advance comes a day after a spokesman for U.N. Secretary-General Ban Ki-moon called for an immediate end to the country's violence. A U.N. peacekeeper was shot and killed Friday when rebels fought government troops and seized Bunagana, a town near the Uganda border southeast of Rutshuru.

M23 comprises former soldiers who mutinied earlier this year, complaining about their treatment in the army. They are believed to be loyal to Bosco Ntaganda, a militia leader wanted by the International Criminal Court on war crimes charges.