A UN envoy said Wednesday that UN troops would help reinforce the Democratic Republic of Congo's borders to stop rebels and arms getting into other countries after the defeat of M23 mutineers.

The United States and other leading UN Security Council members widely welcomed the rout of M23 at closed talks on the conflict-stricken country, diplomats at the meeting said.

But Martin Kobler, the UN representative to DR Congo said the UN peacekeeping mission, officially known as MONUSCO, would strengthen border positions to stop ethnic Hutu rebels of the Democratic Forces for the Liberation of Rwanda (FDLR) crossing into Rwanda.

"We need to reinforce MONUSCO positions near the border to avoid flows of arms across the border, to avoid the FDLR crossing to Rwanda," Kobler was quoted as telling the closed meeting.

UN troops backed an offensive by government forces that defeated M23 rebels who launched an uprising in eastern DR Congo in early 2012.

Rwanda, a temporary Security Council member, has warned that it is ready to intervene in DR Congo, and this message was reinforced by its UN envoy Eugene Richard Gasana. Rwanda is particularly enraged by FDLR operations across the border.

"Rwanda remains fully prepared to use all necessary means to protect its people and territory," Gasana was quoted as telling the meeting.

But the DR Congo government victory was widely praised at the meeting.

UN peace envoy Mary Robinson told the meeting defeat of M23 was a "very special moment" in efforts to halt decades of conflict in eastern DR Congo.

"The wolf at the door, the M23, was threatening civilians, was threatening MONUSCO. We hope that the threat of this wolf at the door is now gone for good," US ambassador Samantha Power told the meeting, according to envoys.