South Sudan's rebels loyal to the former First Vice President Riek Machar said they have started official release of prisoners of war captured since the outbreak of civil war in 2013.

Rebel deputy spokesman Lam Paul Gabriel said their leader Riek Machar ordered the release of war prisoners being held in various areas in the country.

"The chairman and commander in chief of the SPLM/A -IO Riek Machar has officially directed the SPLA-IO forces to release all PoWs and political detainees as mentioned in the Cessation of Hostilities (CoH) agreement effective on 09/01/2018," Gabriel said in a statement extended to Radio Tamazuj.

He revealed that the SPLA-IO group in Western Bar El Ghazal region through its command structure on 11 January handed over three detainees to the International Committee of the Red Cross (ICRC).

He identified the three men released by their group as Angelo Besensio Mangu, Anthony Jabakana, and Natale Arkangelo Bandas.

The move comes after the 14-day deadline agreed in the ceasefire agreement by the warring parties in December 21 last year, in Ethiopia on the release of prisoners of war being held on both sides elapsed last week.

The deal also called on the warring parties to surrender children recruited in their ranks to the UN children's agency (UNICEF) in the stipulated period.