- Members of the South Sudan Opposition Alliance (SSOMA) and an envoy of the government in Juba said they had signed a document on Sunday committing to a December 2017 peace deal.
South Sudan's government and opposition groups who had snubbed an earlier peace deal said they had agreed to a ceasefire from Wednesday, after peace talks in Rome.
Members of the South Sudan Opposition Alliance (SSOMA) and an envoy of the government in Juba said they had signed a document on Sunday committing to a December 2017 peace deal to "avoid any further armed confrontation across the country".
South Sudan, the world's youngest country, descended into civil war in 2013, when President Salva Kiir accused his former deputy and fellow former rebel leader Riek Machar of plotting a coup.
About 380,000 people have died in the conflict and some four million have fled their homes.
Fears have grown in recent weeks that a fragile peace deal will not hold after delays in implementing a unity government and ongoing disagreements.
While peace has largely held across the country, fighting has continued in the Central Equatoria region between government troops and the National Salvation Front, whose leader Thomas Cirillo Swaka signed the agreement in Rome.
'We are ashamed'
"We are ashamed this peace has eluded us," Pa'Gan Amum Okiech, a member of SSOMA's leadership council and interim chairman of another rebel group, the Real-APLM group, said Monday.
"We agree to begin this process of dialogue to reach comprehensive solutions to the crisis," Amum Okiech told journalists, stressing that those solutions would be "inclusive."
Progress on a more recent agreement in September 2018 calling for Kiir to form a transitional unity government with Machar has been delayed over a host of unresolved issues.