South Sudanese Information Minister Michael Makuei told the media in Juba on Thursday the government was aware that Lieutenant General Thomas Cirillo had declared an armed rebellion against the government.
Makuei urged Cirillo to embark on peaceful ways of resolving political grievances.
"If he doesn't denounce what he is doing and come back for national dialogue, so be it. We will see how he progresses and how far he will take over so that he can introduce those whims he which he has in mind," Makuei said.
Cirillo announced the creation of the National Salvation Front, abbreviated to NAS on Monday, and called on the people of South Sudan "to rise up and topple the Kiir regime."
Day of prayers
Makuei said the government would be launching a national dialogue across the nation aimed at improving the implementation of the stalled 2015 peace agreement. He said the launch would start with a national day of prayers on Friday (10.03.2017) which had been called by President Salva Kiir.
Cirillo said the NAS was convinced that "to restore sanity and normalcy to our country, Kiir must go." He also called on South Sudanese to leave the country, saying it was not safe to stay under Kiir's leadership.
The UN refugee agency, UNHCR, said last week 1.5 million refugees had fled fighting a famine in South Sudan for neighboring countries and thousands more were leaving daily.
Cirillo was South Sudan's army deputy chief of staff for logistics until his resignation last month. He said he was stepping aside because of Kiir's inability to govern the country and accused him of carrying out a "tribally engineered war."
The extent of the former general's political and military support both in South Sudan and in the wider region is unclear.
The 17-page letter declaring his rebellion was signed by him alone, raising questions about his ability to launch a broad movement to challenge Kiir.
Ethnic cleansing allegations
South Sudan's civil war began in December 2013 when Kiir accused his deputy, Riek Machar, of plotting a coup. The fighting that followed intially split the country between Kiir's Dinka and Machar's Nuer tribes, but as the war spread so, too, did cracks between other ethnic groups.
Cirillo is from Equatoria, a previously peaceful part of the country that has come under attack in recent months. He is a member of the Bari people which is generally allied to Kiir's Dinka.
He has also accused Kiir of pursuing "ethic cleansing" and looting the country.
A new report drawn up by theUN Commission on Human Rights describes South Sudan as experiencing ethnic cleansing and teetering on the edge of genocide
The report includes new details on deliberate starvation and bombardment of civilians. It describes the use of hate speech by top officials including Kiir.
However, UN Secretary General Antonio Guterres appeared to tone down this assessment of conditions in the country saying the "risks of genocide have considerably diminished."
Guterres was speaking in Nairobi and responding to a reporter's question about the Commission's report.
Ulrich Delius fromGermany's Society For Threatened Peoples takes issue with Guterres' assertion that risks have "diminished." The Secretary General's remarks stood in marked contrast to "the alarming reports by UN human rights experts and human rights organizations," Delius said. The UN should be focusing on respect for human rights and humanitarian relief in South Sudan "more than before."
Cirillo's resignation in February was followed by the departure of the minister of labor Gabriel Duop Lam, who declared his "full allegiance and commitment" to exiled rebel leader Riek Machar.
Two top officials overseeing South Sudan's military courts, Brigadier General Henry Oyay Nyago and Colonel Khalid Ono Loki, also left their posts last month saying high-level interference made it impossible to discipline soldiers accused of rape and murder amid the nation's civil war.
"Continued fractionalization, the arming of opposition figures and violence is only going to make things worse for the people of South Sudan" Chatham House research associate Ahmed Soliman told DW.
Waakhe Simon Wudu in Juba contributed to this report