KINSHASA: Fourteen aid workers kidnapped two days ago by unidentified assailants in the eastern Rutshuru region of Democratic Republic of Congo have been released, the United Nations (UN) said on Tuesday.

Dozens of people have been kidnapped in Rutshuru this year by armed militias and criminal gangs. The area is still plagued by rebel groups following a 1998 to 2003 war that killed millions, mostly from hunger and disease.

The group of 14 kidnapped on Sunday were employees of a Congolese non-governmental organisation.

"We are very happy to learn that the 14 aid workers kidnapped on Sunday have been released," the UN Office for the Coordination of Humanitarian Affairs (OCHA) in Congo said on its Twitter feed.

Local government officials could not be reached for comment.

A spokesman for OCHA did not immediately have further details on the circumstances of the release, nor could he confirm their nationality.

Rutshuru's mountainous terrain, which abuts the Rwandan border, has been the site of several home-grown and foreign-backed insurgencies and remains fertile ground for many of eastern Congo's dozens of armed groups, who traffic its rich natural resources.