The United Nations mission in Congo says unarmed South Sudanese refugees have taken 13 staffers hostage at a U.N. camp in eastern Congo, demanding they be moved to another country.

Daniel Ruiz, the head of the North Kivu U.N. bureau, said Tuesday the former fighters at the Munigi base in Congo's North Kivu province are not armed, but are demanding asylum in Uganda, Kenya or Ethiopia.

The refugees are among a group of about 530 who fled South Sudan last year and have been staying at the U.N. camp. Most were fighters with the opposition movement of South Sudan's former vice president, Riek Machar, who clashed with forces loyal to President Salva Kiir.

The hostage-taking came after eight fighters from the Sudanese People's Liberation Movement of Machar were repatriated to South Sudan Friday.