South Sudan's first vice-president designate Riek Machar said on Thursday he would return to the capital Juba on April 18, the first time since conflict broke out in December 2013 between forces loyal to President Salva Kiir and rebels allied with Machar.

Dr Machar leads the armed opposition faction of the Sudan Peoples’ Liberation Movement (SPLM-IO).

"I am therefore confirming the date of my arrival to be April 18 and thereafter form with President Kiir the Transitional Government of National Unity and hold the Transitional National Council of Ministers," Dr Machar said in a letter to the Joint Monitoring and Evaluation Commission which is monitoring the implementation of a peace deal signed between Machar and Kiir.

In an earlier interview with The EastAfrican , Dr Machar said that he would return as soon as the designated 1,370 SPLM-IO force is in place.

He said he has already made a tentative list for 10 Cabinet slots that were given to the former rebels and will refine it once in Juba in consultation with his supporters.

The portfolio balance reached in January gave President Salva Kiir 16 slots, Dr Machar 10 slots and two each for former detainees and other political parties in the 30-member Cabinet of National Unity.