Mr Elbow was officially appointed last year by Riek
Machar as the SPLM/A-IO Youth Leader in Ethiopia.
At the time, in 2013, Dr
Machar was South Sudan's Vice President, and as tension persisted between him and President Kiir, the Head of State accused his VP and 10 other leading SPLM figures of plotting a coup against him.
Machar's office said he would attend peace celebrations hosted by his longtime rival, President Salva Kiir.
"After a 10-hour-long meeting, the parties agreed … there will be four vice presidents and Dr Riek
Machar will be reinstated as first vice president," the statement said.
The war began when Kiir accused
Machar, his former deputy, of planning a coup.
In a reference to
Machar's perceived ambition to run for the presidency, Makwei urged
Machar to "abstain from politics" until the elections.
The statement did not reveal which country
Machar had gone to.
Government troops were battling renegade forces loyal to Mr
Machar, as well as a pro-Machar tribal militia known as the "White Army," said military spokesman colonel Philip Aguer.
Machar also confirmed to the BBC that the forces fighting the government were under his command and now control much of the country.