Stop South Sudan war, Kiir told

Debris outside the Kali-Ballee Mosque in the oil town of Bentiu, Unity State, on April 15, 2014. "More than 200 civilians were reportedly killed and over 400 wounded," the UN mission in the country said, adding there were also massacres at a church, hospital and an abandoned UN World Food Programme (WFP) compound. AFP PHOTO / HO / UNMISS

Washington and the United Nations are pushing South Sudan leaders to resolve the ongoing crisis.

In a telephone call to South Sudan President Salva Kiir on Tuesday, UN Secretary-General Ban Ki-moon “called for an immediate halt to the vicious fighting and the appalling killing of South Sudanese civilians.”

US Secretary of State John Kerry, who is expected to meet with South Sudan rebel and government peace negotiators on Wednesday in Ethiopia, also urged the South Sudan leader to stop military offensives. (READ: Kerry heads on Africa tour amid fears over S. Sudan war)

In an interview on Monday with Voice of America, Mr Kerry said the Obama administration is looking “very, very closely” at the option of imposing sanctions on warring parties in South Sudan.

The UN has also emphasised the need for President Kiir to bring the perpetrators of the “completely unacceptable attack” on a UN mission (Unmiss) base in Bor to justice.

BENTIU MASSACRE

At least 30 civilians were killed when a mob reportedly comprised mainly of Dinka broke into the UN installation in Bor on April 17.

Hundreds more died in a rampage by Nuer fighters who attacked a mosque, church and hospital in Bentiu during the same period.

The UN chief further urged President Kiir to “intervene personally to stop the negative campaign against Unmiss staff and issue a public statement to this end.”

Mr Ban also emphasised the need to ensure accountability for “the ethnically motivated killings in Bentiu.” (READ: The killing fields of South Sudan)

The US Government has reiterated its stance on rebel forces warning them to stop their attacks. The conflict has taken on personal as well as tribal dimensions, Mr Kerry said.

South Sudan's hope for peaceful development is being “tugged downwards by personal ambitions and personal animosities,” he added.