South Sudan's rebel commander Riek Machar has said his forces were not behind the massacre of hundreds of people in the contested town of Bentiu.
The United Nations has accused them of killing more than 200 people in one mosque alone when they re-captured the town last week after a battle with government forces.
Machar, who was dismissed as vice president by President Salva Kiir in July 2013, told Al Jazeera on Tuesday that his rebels would not kill their own people.
"I contacted the field military commander in Bentiu who told me that such accusation is false. First of all we respect our people, and the majority of the forces are from the region and we can't kill our citizens," Machar said.
Failed coup charge
Thousands of people in South Sudan have been killed in violence and more than one million people have been forced to leave their homes since December when pro-Kiir troops and those loyal to Machar began to fight along ethnic lines.
Machar was accused by Kiir of a failed coup in December.
Though Machar denied being involved he praised the rebel movement that he is leading.
South Sudan's foreign minister, Barnaba Marial Benjamin, told Al Jazeera on Tuesday that he believed Machar's rebels were responsible for the Bentiu killings.
"It is his responsibility because these are his rebels," Benjamin said.
The UN condemned what it called the "targeted killings" and wounding of hundreds of civilians based on their ethnic origins in Bentiu.
The UN's mission in South Sudan said on Monday hundreds of civilians were killed or wounded after rebel forces took control of the capital of the oil-producing Unity state last week.
Toby Lanzer, the UN's top humanitarian official in South Sudan, said in Twitter posts late on Sunday that there were shocking scenes of atrocities, with "bodies of people executed'' lying in Bentiu's streets.
FM station used
Lanzer told Al Jazeera on Monday that people "associated with the opposition" had used an FM radio station to broadcast hate speech in the town.
"With hate speech and violence continuing as they are, we're going to have an even greater catastrophe on our hands at the end of this year," he said.
"I think the saddest testament to the current situation is that we have had members of all communities, even those accused of perpetrating these crimes, fleeing to the UN base."
"We had 5,000 civilians a week ago in our base, now we have 22,000 people. We have just one litre of portable water per person for today.
“It is hard to believe that just a few months ago South Sudan was at peace.
"People are on the brink of disaster. It is imperative the leaders recognise the crisis into which they have plunged their nation."