South Sudan rebel leader Riek Machar late Tuesday left Sudan for South Africa after two months of staying in the capital Khartoum for medical treatment.

"I thanked the government of Sudan for the hospitality and I want to announce here that I'm heading South Africa for medical treatment,” Machar told a news conference at Khartoum Airport.

Machar was hospitalized in Khartoum in August after he fled South Sudan, where widespread clashes were breaking out between the rivals in its civil war.

The rebel leader, formerly South Sudan’s vice president, declared that he will work to bring down the government of President Salva Kiir.

He vowed that he will rework his movement's political and military capabilities to topple Kiir.

He added, however, that he is prioritizing a political solution for the crisis in South Sudan.

Sudan and South Sudan have long exchanged accusations over support to rebels in both countries.