JUBA - South Sudan's army says it has seized back full control of the strategic town of Malakal after almost a week of bitter street fighting, the last major settlement under rebel control.
Malakal's recapture, one of the main battlefields since fighting erupted in the country last month, comes just two days after government troops celebrated the retaking of Bor, another key town and capital of Jonglei state.
Thousands have been killed and half a million civilians have been forced to flee the fighting between troops loyal to President Salva Kiir and rebels loyal to his sacked deputy Riek Machar. The conflict entered its sixth week on Monday.
But the recapture of the final large town under rebel control opens up the possibility of a shift in ceasefire talks deadlocked for two weeks, with some suggesting the government had been reluctant to strike a deal while rebels still claimed urban centres.
But rebels are reported to remain powerful and in control of large areas of the countryside.
"Malakal is finally in the hands of the SPLA (South Sudan's army)... they (the rebels) were flushed out of the town," army spokesman Philip Aguer said.
The United Nations says that atrocities including war crimes are reported to have been committed by both sides, and on Sunday warned that soldiers had tried to forcefully enter a UN base sheltering thousands of civilians.
Secretary General Ban Ki-moon said he was "particularly disturbed" that UN staff were threatened by government troops when peacekeepers blocked soldiers from entering their base in Bor.
The army has denied the incident, saying that they wanted to investigate reports rebels may have thrown off their uniforms to hide in the UN base, claims the UN has in turn denied.
But Ban said the incident was "just one of a growing number of violations" of the UN accord with the government "making it increasingly difficult" for peacekeepers to implement their mandate.
African Union Commission chief Nkosazana Dlamini-Zuma on Monday flew to Juba to meet President Kiir in a bid to help broker a deal between the rival forces.
Regional nations are mediating talks in neighbouring Ethiopia but have already been drawn into the brutal conflict, with Ugandan troops battling alongside government forces.
Rape, murder, devastation
Rebels staged a fresh attack on Malakal last week to seize the riverside town, the capital of oil-producing Upper Nile state, which has been badly damaged in the fighting and has changed hands three times.
Over 22,00 civilians have been sheltering at the United Nations' base in Malakal, with dozens wounded even there as stray bullets hit the overcrowded compound and peacekeepers fired warning shots to protect them.
But the rebels are reported to still control large areas of the countryside.
Bor was left devastated by the battles, with corpses littering the streets and scores of buildings razed to the ground, according to an AFP reporter who visited the town on Sunday.
Civilians recounted grim stories of how the rebels gang-raped and murdered sick patients in the town's hospital.
South Sudan erupted into conflict on December 15 in what Kiir called a coup attempt by Machar, whom he sacked in July. The former vice president denies the charge and accuses his ex-boss of trying to purge his rivals.
The fighting has spiralled into ethnic killings between members of Kiir's Dinka people -- the country's largest group -- and Machar's Nuer.
The violence is rooted in decades-old grievances between former rebels turned political leaders, combined with unhealed wounds left over from the two-decades long civil war that preceded South Sudan's independence from Khartoum in 2011.
Last week, the United Nations' top human rights envoy Ivan Simonovic detailed reports of mass killings, sexual violence and widespread destruction.
The South Sudanese government and rebels are holding peace talks in the Ethiopian capital, but they have made little concrete progress.
Talks are being mediated by the East African regional bloc IGAD, even though Uganda is a key member and the rebels have expressed concern about its neutrality.