A spokesman for U.N. Secretary-General Ban Ki-moon says he is seriously concerned over the killing of a U.N. peacekeeper in the eastern Democratic Republic of Congo.

Mr. Ban is calling for an immediate end to the violence carried out by armed groups there. He has extended condolences to the family of the victim and to the government of his native India.

The U.N. peacekeeper was shot Friday when rebels fought government troops and seized a key border crossing. The deadly incident took place in the town of Bunagana near the Ugandan border.

Vianney Kazarama, a spokesman for the rebel group M23, told VOA Friday the town is in rebel hands.

M23 is comprised of 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.

Congo's government had tried to integrate Ntaganda's men into the armed forces as part of efforts to bring calm to the country's volatile eastern provinces.

Rwanda has denied charges, contained in a recent United Nations report, that it is providing material and financial support to the M23 movement. Last week, the United States called on Rwanda to end such support to the rebels.