Thousands of young men loyal to South Sudanese rebel leader Riek Machar are marching on the strategic town of Bor, raising fears that fighting between rival army factions will push the country into civil war.
About 25,000 youths from Machar’s tribe are marching on Bor, Information Minister Michael Makuei Lueth said on Saturday.
"He has decided to mobilize the youth in the name of his tribe," Lueth said.
The South Sudanese army is currently in control of Bor, the capital of Jonglei state the army had captured from the rebels.
On Friday, the government agreed to a ceasefire with the rebels and promised to release eight of 11 high-ranking politicians captured over an alleged coup plot.
"We have agreed in principle to a ceasefire to begin immediately, but our forces are prepared to defend themselves if attacked," the government said.
The political crisis in South Sudan began two weeks ago after President Salva Kiir accused Machar of attempting the coup. Reports say thousands of people have been killed in the violence since then.
The fighting between troops loyal to Kiir, who is from the Dinka ethnic group, and opposition leader Machar, a Nuer, erupted around Juba on December 15.
The South Sudanese president accused his archrival Machar of attempting to topple his government, but he said the coup attempt had been foiled.
The government’s promise to release the eight political figures arrested in the aftermath of the fighting suggests Kiir may have agreed to end hostilities against rebels accused of trying to overthrow his government.
However, Machar rejected the ceasefire offer, saying that any truce should be negotiated by delegations from both sides.
South Sudan gained independence in July 2011 after its people overwhelmingly voted in a referendum for a split from the North.
The government in Juba is grappling with rampant corruption, unrest and conflict in the deeply impoverished but oil-rich nation, left devastated by decades of war.