Kenya opposition leader visit South Sudan rebel leader in Pretoria.
President Kiir and Dr Machar are expected to hold face-to-face talks in Sudanese capital Khartoum before the end of June.
The meeting is said to have been an initiative of Mr Odinga, Sudanese President Omar al-Bashir and Ethiopian Prime Minister Abiy Ahmed.
South Sudan’s rebel leader Dr Riek Machar has pledged to back efforts to restore peace and stability in his war-torn country.
“The status quo should not stand. Something will change,” he said after Kenyan opposition leader Raila Odinga visited him in South Africa where he has been under house arrest since November 2016.
“This is part of the effort to reconcile the warring parties with the view of ending years of civil war that has crippled the world's newest country," Mr Odinga, who represented Kenya, said of his Friday visit.
He had met South Sudanese President Salva Kiir in Juba a fortnight ago.
President Kiir and his nemesis Dr Machar are expected to hold face-to-face talks in Sudanese capital Khartoum before the end of June.
Dr Machar leads the Sudanese People’s Liberation Movement-In Opposition (SPLM-IO), the main and largest rebel group.
The Inter-Governmental Authority on Development (Igad) has been mediating the South Sudan peace talks, since the war broke out in December 2013, two years after seceding from Sudan, with little progress.
In March, Igad Council of Ministers resolved that Dr Machar be released from house arrest and relocated to another country that does not share borders with South Sudan on condition that he renounces violence and does not undermine the peace talks.
However, the SPLM-IO chief says his release should be without conditions and that his security needs to be guaranteed.
According to a source close to the talks between Mr Odinga and Dr Machar, the Kenyan leader is said to have assured the SPLM-IO leader of his security in Nairobi and those of other rebel leaders.
"It is being done in good faith in the hope that it can encourage honest participation," said the Kenyan diplomatic source.
"Security guarantees could be a good catalyst but we wait to see if other issues will be ironed out."
South Sudan Information Minister and government spokesman, Michael Makuei Lueth said the planned meeting was the initiative of Mr Odinga, Sudanese President Omar al-Bashir and Ethiopian Prime Minister Abiy Ahmed.
“The position of President Kiir is that, yes he will meet Riek Machar but this should be with involvement of Igad because he does not want it to be seen as if it is something done outside Igad,” he told The EastAfrican in Juba.
