The former South Sudan chief of general staff, Gen Paul Malong, has created a new rebel group that is likely to complicate issues ahead of the third round of peace talks slated for April 26.
In a statement on Monday, Gen Malong said his South Sudan United Front (SS-UF) was formed to push for comprehensive constitutional review to introduce a new system of government including federalism.
The general, who was sacked last May and placed under house arrest for nearly six months, said his former longtime ally, President Salva Kiir, must leave power if South Sudan is to reach any peace agreement.
“We already have an agreement for three years that has yielded no fruit. It therefore goes without saying that President Kiir cannot and should not be entrusted with midwifing the revitalisation agreement,” he said.
South Sudan, which seceded from Sudan in 2011, plunged into civil war in December 2013 after President Kiir sacked his deputy Riek Machar.
The August 2015 peace agreement brokered by the Inter-Governmental Authority on Development (Igad), a nine-member states regional bloc, with backing from the United States, Britain and Norway, known as Troika, is yet to be fully implemented.
Several cessations of hostilities agreements have also been violated.
Gen Malong said SS-UF will join the South Sudan Opposition Alliance that is part of the revitalisation talks led by Igad.
"We wish to further state our intention to participate in the Revitalisation Forum scheduled to commence on 26th April in Addis Ababa, Ethiopia," the statement read, adding that SS-UF would also append its signature to the addendum to the Cessation of Hostilities already signed by the other opposition parties.
Gen Malong's statement comes just weeks after his meeting with Sudan's Intelligence chief Salah Al-Gosh in Khartoum, raising alarm in Juba that he could seek support to foment a rebellion against Kiir's administration.
Last week, the government seized three of his houses in Juba.
Gen Malong lives in Nairobi after being freed from house arrest in November when he was allowed to travel to seek medical care.
In January, President Kiir declared the influential former military chief a rebel and wrote to Kenya seeking his deportation.