The Special Representative of the UN Secretary-General, Ellen Margrethe Loj has called for the release of 89 children kidnapped in Wau Shilluk last month.
She made the call during a visit to Malakal with the U.S Ambassador to South Sudan, Charles Twining.
During the visit, Loj met with the Deputy Governor of Upper Nile State and ministers of the state government.
Earlier, UNICEF said the children kidnapped in the area were forcibly recruited as child soldiers by forces belonging to Johnson Olony.
The SPLA said it had sent a team to investigate the allegation.