Addis Ababa (AFP) - Heavyweight international powers will pressure South Sudan's leaders to end civil war, diplomats said Thursday, with the African Union, United Nations, United States and China to kickstart stalled peace talks.
Over a year of talks mediated by East Africa's eight-country IGAD bloc have failed to make headway, with the last attempt breaking down last month, and rebel forces accusing regional nations of bias.
The UN Security Council has passed a resolution paving the way for targeted sanctions.
Now diplomats have told AFP they plan a boosted "IGAD-plus" to bring in extra powers to add pressure.
"The new IGAD-plus formula will bring African peer pressure on the parties, as well as on the IGAD countries to close ranks," a diplomat said.
South Sudan won independence from Khartoum in 2011, but civil war broke out in December 2013 after its president, Salva Kiir, accused his sacked deputy Riek Machar of attempting a coup.
Kiir and Machar "agree that they have agreed on almost everything and none of them can make further compromises," one diplomat said. "That is why a broad international alliance would help the parties make the last difficult choices."
While IGAD-led talks in Ethiopia brokered a string of ceasefire deals, all swiftly collapsed.
- 'Dealing with whole continent' -
Now, alongside the UN, extra nations to be brought in include five representing the African Union - Algeria, Chad, Nigeria, Rwanda and South Africa.
China is also to join. Beijing is the largest investor, operator and buyer of South Sudan's oil, and some 700 troops of its troops are in the UN peacekeeping force.
Washington, who played a key role in South Sudan winning independence from Khartoum in 2011, will also take part, alongside former colonial power Britain and Norway, a key longtime aid donor to South Sudan.
The three nations are often dubbed "The Troika" in peace efforts.
Rebel chief Machar has opposed IGAD efforts in part because he accuses it of favouring the government, with bloc member Uganda having sent in troops to bolster Kiir's forces.
"Divisions within IGAD countries have limited the effectiveness of the role IGAD can play," said Solomon Dersso, from the Institute for Security Studies (ISS) in Addis Ababa.
"Kiir and Machar were able to play very well the different interests -- they are now dealing with the whole continent."
Fighting has left tens of thousands dead and provoked a major humanitarian crisis, and over half of the country's 12 million people need aid, according to the UN.