FILE - South Sudan's rebel leader Riek Machar.
FILE - South Sudan's rebel leader Riek Machar.

South Sudan opposition leader Riek Machar is in Khartoum for medical treatment, a Sudanese minister said Tuesday.

Information Minister Ahmed Bilal told state media Machar was brought to Sudan in "serious condition."  Bilal said the opposition leader is suffering from some sort of chest infection and a problem with his leg, and is “in very bad condition because he kept walking for more than 15 days.”

Bilal said Juba has been notified of the situation.

South Sudan's President Salva Kiir sacked Machar from his post as first vice president after renewed fighting in the capital, Juba, last month between forces loyal to the longtime rivals. The clashes forced tens of thousands of people to flee.

Machar withdrew to the bush during the fighting and was picked up this month by U.N. peacekeepers in the Democratic Republic of Congo with a leg injury. His spokesman earlier said that Machar left South Sudan to evade Kiir's forces and that his injury is not serious enough to require medical attention.

"Dr. Riek Machar's health is stable currently and he will remain in the country under comprehensive health care until he leaves to a destination of his choice to complete his treatment," Bilal said, refusing to provide any more details.

When asked who accompanied Machar to Khartoum, Bilal responded, “He is alone.”

Machar and Kiir have long been rivals, even before South Sudan's independence in 2011, when they were both commanders in the SPLA force that fought Sudan's Khartoum-based government.

But by December 2013, the political rivalry between Kiir, an ethnic Dinka, and Machar, a Nuer, had again boiled over into a civil conflict, which often followed ethnic lines.

The two men signed a peace deal in August 2015. Under that deal, Machar returned to Juba in April to resume his role as first vice president. But fighting flared last month and he was then dismissed.

The U.S. and the United Nations have urged both sides to make amends to bring peace to the world's youngest nation.

Last week, the U.N. Security Council voted to authorize sending an extra 4,000 troops to the country to bolster the existing U.N. mission, which South Sudan said it was considering.