Machar arrived in South Africa in October for medical treatment after sustaining a leg injury.
Monyela said on Wednesday in Johannesburg that the rebel leader “is a guest of the South African government.’’
“He is in South Africa at the request of the East African bloc Intergovernmental Authority on Development (IGAD)."
IGAD had previously hosted peace talks between the South Sudanese government and the rebels in the Ethiopian capital, Addis Ababa.
Machar arrived in South Africa in October for medical treatment after sustaining a leg injury while fleeing fighting between his troops and the army in South Sudan’s capital, Juba, in July.
The rebels said last month that Machar had flown from South Africa to Addis Ababa, where he was briefly detained at the airport to prevent him from going to a rebel base on the South Sudanese side of the Ethiopian border.
Ethiopia was reportedly concerned that Machar’s presence could spark more clashes in violence-plagued South Sudan.
But rebel spokesperson Dickson Gatluak said that Machar returned to South Africa on Nov. 22 because his Ethiopian visa “was not ready.’’
Gatluak said the rebel leader was in Johannesburg but denied that he was under house arrest.
“The government of South Sudan wants Machar to be silent in exile,” Gatluak said, adding that the relationship between the rebels and the South African government “is still intact.”