The leader of South Sudan’s rebels said Wednesday that the country’s civil war would continue as long as President Salva Kiir remained in power.

The leader of South Sudan's rebels said Wednesday that the country's civil war would continue as long as President Salva Kiir remained in power.

"We don't feel like we have a peace partner with Salva Kiir," Riek Machar told reporters in a luxury hotel in the Kenyan capital, saying that previous ceasefires he had signed with the government during the course of the 18-month-old conflict were "born dead".

"The people of South Sudan did not deserve to go back to war, but this was caused by the actions of President Salva Kiir, who we ask to resign today," Machar said.

"Should President Kiir remain adamant and refuse to hand over power back to the people, then the citizens have every right to rise up and overthrow his regime."

The comments came as South Sudan, the world's youngest nation, prepares to mark the fourth anniversary of its independence from Khartoum on Thursday, an event that marked an end to decades of war but only provided a brief respite from conflict.

The civil war in the new nation began when Kiir accused Machar, a former vice president, of planning a coup, setting off a cycle of retaliatory killings that has split the country along ethnic and tribal lines.

Fighters on both sides are accused of atrocities, and analysts believe tens of thousands of people have died since the war began.

The United Nations has also described South Sudan as being "lower in terms of human development than just about every other place on earth."