The United Nations' top human rights official has said South Sudan is "close to calamity", and said it was the responsibility of leaders on both sides of a civil conflict to ensure the safety of civilians.

Navi Pillay, the UN's high commissioner for human rights, said on Wednesday that she was "appalled by apparent lack of concern displayed" by rebel leader Riek Machar and and the president, Salva Kiir, about risk of famine in the country,

"The prospect of widespead hunger and malnutrition being inflicted on hundreds of thousands of their people, because of their [Riek and Machar's] personal failure to resolve their differences peacefully, did not appear to concern them very much," she said.

Her comments came a day after she and Adama Dieng, the UN special adviser on the prevention of genocide, met Machar on Tuesday in Juba.

Pillay relayed the UN's concerns to Machar following a massacre on April 15 by rebel fighters who left the town of Bentiu littered with bodies after slaughtering civilians in the town mosque, the hospital and on streets.

Child soldiers

According to Pillay, more than 9,000 children have been recruited as soldiers in South Sudan's brutal four-month long civil war by both government and rebel forces.

Dieng said that investigations were important, but that peace in South Sudan was the ultimate goal.

"What is critical is that the hostilities have to be ceased and that both leaders come together so that the people of this country are not betrayed," he said.

Negotiations between forces loyal to Kiir and Machar have failed to advance since the January 23 signing of a ceasefire which never took hold.

The UN accused the rebels in early April of hunting down hundreds of people in a hospital, church and mosque in Bentiu and killing them based on ethnicity and nationality.

After that massacre, Dinka residents of Bor in Jonglei state attacked a UN base where about 5,000 people, mostly Nuer, were sheltering. At least 58 people were killed and nearly 100 wounded, including two UN peacekeepers.

Members of the UN Security Council are considering sanctions on South Sudan's warring parties.

Source: Agencies