South Sudanese armed group the Cobra Faction has released up to 250 child soldiers, including four girls, during a formal ceremony in the village of Lekuangole, in Jonglei State.
The release is the third such hand over of children following a peace agreement signed between the faction and the South Sudan Government's national disarmament, demobilisation and reintegration commission (NDDRC).
Over the next two days, it is excepted that a further 400 children will be released by the group, which has admitted to Unicef that it has up to 3,000 child soldiers in its ranks.
Unicef South Sudan representative Jonathan Veitch said the release takes the number of demobilised child soldier to 1,314.
Veitch said: "Of the 660 children set free in Pibor and Gumrok, 200 children have been reunited or are about to be reunited with their families. In a short time that figure will double.
"While we welcome freedom for the children, we are also deeply disturbed by the hundreds of children being abducted in Upper Nile and Unity States.
"Unicef condemns this violation of human rights and calls on all parties to release the children. Unicef stands ready to support their demobilisation."
The newly released children were demobilised by the NDDRC with their weapons and uniforms exchanged for civilian clothes, and were later transferred to a Unicef interim care centre in the village where they are provided with food, shelter and medical care.
Supported by its partners, Unicef will now initiate the process of tracing their families, and providing psychosocial support, where necessary.
According to media reports, more than 12,000 children are currently being used by the South Sudanese armed forces and rebel groups on both sides of the conflict in the country.