South Sudan rebels have rejected a government peace offer to return to a system of 10 states, setting back hopes of ending a six-year war that has left 380,000 dead.
President Salva Kiir said on Saturday that he would compromise by cutting the current 32 regional states down to the original 10, a key rebel demand, to pave the way for a unity government.
But Mr Kiir also proposed creating three "administrative areas" – Pibor, Ruweng and Abyei.
Rebel chief Riek Machar said he opposed those three areas, saying it "cannot be referred to as reverting to 10 states" and "as such cannot be accepted".
"We therefore call upon President Kiir to reconsider this idea of creating administrative areas," he said on Sunday.
Mr Machar warned the three areas risked causing further problems, calling the issue a "Pandora's box".
Mr Kiir and Mr Machar, who lives in exile, are under increasing international pressure to resolve their differences before a February 22 deadline.
Mr Machar has repeatedly said he could not return to his old job as vice president if the country's structure did not return to its original form.
The number of states is contentious because the borders will determine the divisions of power in the country.
When it gained independence from Sudan in 2011, South Sudan had 10 states, as set out in its constitution.
Mr Kiir increased that in 2015 to 28, then 32. He issued an order on Saturday relieving governors of all the 32 states of their posts.
He has said the final matter of states would be debated once the unity government forms.
Of the three areas, the most contentious is thought to be oil-rich Ruweng, in the north.
Oil provides almost all of the government's revenue in South Sudan.
Ruweng has been one of the most heavily fought over areas in the civil war and is claimed by both the Dinka people of Mr Kiir and the Nuer of Mr Machar.
Abyei, another of the three areas, is a border zone contested with neighbouring Sudan.
Pibor lies in the eastern Jonglei region, an area long troubled by militias and rebels fighting over local grievances.
Mr Kiir and Mr Machar are old rivals who have fought and made up several times. Their latest agreement came when they signed a peace deal in September 2018, pausing the bloodshed that erupted in 2013 when the president accused his former deputy of plotting a coup.
They agreed to come together in a coalition in May 2019.
However, disputes over territory and security arrangements dogged negotiations and the deadline was missed, followed by another six months later.
In November, the pair were given 100 more days to resolve these sticking points. That extension ends on Saturday.
The Intergovernmental Authority on Development, a bloc of eight East African nations that is leading the process, warned last week that any extension beyond February 22 was "neither desirable nor feasible".
