Armed men have reportedly abducted not less than 89 boys from a camp in the northern city of Malakal that hosts thousands of people displaced by fighting between the army and rebels.
According to UNICEF, the unidentified gunmen went from house to house, seizing boys that were over the age of 12.
It was gathered that Human Rights Watch last week accused both sides of using child soldiers, a charge which was denied by the government.
Uprising in South Sudan began in 2013 after President Silva Kiir accused his sacked deputy Riek Machar of plotting a coup.
Although, Machar denied the allegation, he however raised a rebel force to fight the government.
According to UN, 12,000 children were used as child soldiers across South Sudan last year and about 1.5 million people have been displaced by the fighting and 2.5 million are facing severe food shortages.