The UN did not say however whether any fighters had handed in weapons and appeared to be pulling back from an immediate confrontation.
UN spokesman Martin Nesirky yesterday said the UN Stabilization Mission in DR Congo (MONUSCO) and the Congo army "have now established a security zone in the greater Goma area and along the Goma-Sake axis."
Goma is at the heart of a resource-rich region in which millions have died in conflict in the past two decades.
"The objective of the security zone is to provide better protection to over one million civilians -- including internally displaced persons -- living in the area," said Nesirky.
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"UN peacekeepers and Congolese security forces will continue their patrols to ensure that the area is free of unauthorized weapons."
The spokesman said "the security zone is not an offensive operation and is not targeted at any one armed group."
M23 rebels, who have been battling government forces for more than a year, launched a new offensive against government forces around Goma on July 14.
However, M23 rebels are not inside the security zone. Diplomats said the zone may have been set up as a warning to M23, who briefly took Goma last November, not to push any closer to the city.
While renewing efforts to seek a political settlement to the region's troubles, the United Nations has set up a new offensive 'intervention brigade' to take on M23 and other armed groups in eastern DR Congo.
It also announced yesterday that it has ordered its first unarmed surveillance drones from an Italian company to patrol volatile regions of eastern DR Congo.
Nesirky said the drones, to be provided by Selex ES, a subsidiary of the Italian giant Finmeccanica, should be deployed "in coming weeks.