Direct peace talks have begun between the South Sudanese government and rebel forces for the first time since a recent escalation in violence, despite reports of renewed fighting across several parts of the country.
The face-to-face negotiations started in Ethiopia on Sunday between representatives of President Salva Kiir and former Vice President Riek Machar, as part of regional and international efforts to end the deadly fighting that broke out in the young country last month.
United States Secretary of State John Kerry urged the two sides not to use the talks as a "gimmick" to buy time.
"Negotiations have to be serious, they cannot be a delay, [a] gimmick in order to continue the fighting and try to find advantage on the ground at the expense of the people of South Sudan," Kerry told reporters while on a visit to Jerusalem on Sunday.
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The conflict in South Sudan erupted on December 15, pitting army units loyal to the president against a loose alliance of ethnic militia forces and mutinous army commanders headed by Machar.
The government has accused Machar of attempting a coup. Machar has denied the accusation, and in turn accuses the president of conducting a violent purge of his rivals.
At least 1,000 people have been killed, and 200,000 displaced since the fighting began.
On Sunday, Ethiopian government spokesman Getachew Reda said IGAD, the East African regional bloc brokering the talks, was trying to convince South Sudan's government to release 11 detainees, many of them former senior government officials.
Reda said it was important "for the government of South Sudan to go the extra mile as a goodwill gesture."
"The prisoners can have their day in court, but IGAD could expedite the process -- one suggestion is bailing out and transferring the detainees to IGAD's custody," he said.
But the spokesman for South Sudan's government delegation, Information Minister Michael Makuei, rejected the proposal, instead blaming Machar of starting the fighting with an attempted coup.
"His attempt to overthrow a democratically elected government is an established fact," Makuei said.
"We are being told to negotiate with the rebels. But any rebels who have fallen in our hands will have to answer why he or she decided to take up arms against a democratically elected government," he added.
Meanwhile, fighting continued in the oil-producing Unity and Upper Nile states in the north on Sunday.
Army spokesman Philip Aguer said that government forces were advancing on the two state capitals of Bentiu and Malakal, currently in rebel hands, and that troops were preparing to retake Bor, capital of Jonglei.
Fighting also broke out in the capital Juba late on Saturday, with exchanges of gunfire heard coming from a district in the south of the city. Calm returned in the early hours of the morning.
The fighting caused more Juba residents to try to move south to Uganda, adding to the nearly 200,000 people who have already been displaced by three weeks of conflict.
UN peacekeeping bases have also been overwhelmed with civilians seeking shelter, many of them fleeing ethnic violence pitting Kiir's Dinka community against Machar's Nuer tribe.