South Sudan's main rivals were at loggerheads Friday over who will control the country's 10 internal states, an issue that analysts and diplomats worried could jeopardise a power-sharing deal reached earlier this year.

South Sudan President Salva Kiir and rebel leader Riek Machar agreed Thursday to form a unity government on Saturday, a long-delayed step towards ending six years of war.

South Sudan President Salva Kiir on Friday dismissed international calls for compromise with his foes to break a deadlock that threatens a ceasefire in their six year war.

President Salva Kiir returned Wednesday from talks on South Sudan's future to organised crowds calling him a hero, as diplomats warned time was short to strike a deal for peace.

The latest round of peace talks between South Sudan's two rival leaders has failed to strike a deal on the vital issue of internal boundaries, mediators said on Friday.

South Sudan President Salva Kiir and rebel leader Riek Machar held fresh talks Wednesday in a bid to break a deadlock over states and internal borders in the troubled country, in order to form a unity government next month.

South Sudan President Salva Kiir and opposition leader Riek Machar agreed Tuesday to form a unity government by a February deadline, as they face international censure over faltering peace talks.

South Sudan President Salva Kiir on Friday said a new delay to set up a power-sharing government was "endurable" as he vowed to honour a peace deal funding pledge for a unified army.

South Sudan President Salva Kiir and rebel leader Riek Machar will hold rare face-to-face talks Thursday in Uganda, their representatives said, as time runs out for the rivals to form a power-sharing government.

South Sudan's exiled rebel leader Riek Machar arrived in Juba on Saturday in a bid to salvage a peace deal with less than a month to go until he is to form a government with President Salva Kiir.

Sudanese Prime Minister Abdallah Hamdok will attend peace talks in the South Sudan capital Monday with rebel leaders from several Sudanese states, said official sources in Juba. "Tomorrow's meeting is to mark the launching of Sudan's peace talks," Ateny Wek Ateny, spokesman for South Sudan's President Salva Kiir, told AFP Sunday.

South Sudan's exiled rebel leader Riek Machar arrived in Juba on Monday for the first time in a year to meet his rival, President Salva Kiir, and try salvage a stalled peace agreement.