South Sudan's President Salva Kiir has sacked his army chief after rebels seized a major oil hub, unleashing two days of ethnic slaughter in which the UN says hundreds of civilians were massacred.
Rebels loyal to sacked vice-president Riek Machar seized Bentiu last week. The United Nations says they hunted down civilians sheltering in mosques, churches and a hospital, in a wave of ethnic killings.
The president gave no reason for removing general James Hoth Mai, a move announced on national television on Wednesday, but sources attributed the decision to recent military setbacks in the oil-rich north of the country. His successor was named as general Paul Malong.
Kiir also sacked his intelligence chief, General Paul Mach, replacing him with General Marial Nour Jok.
South Sudan's army has been fighting the rebels since unrest broke out on December 15, but the conflict has taken on an ethnic dimension, pitting Kiir's Dinka tribe against militia forces from Machar's Nuer people.
The conflict in South Sudan, which only won independence from Sudan in 2011 and is the world's youngest nation, has left thousands dead and forced about a million people to flee their homes.
The insurgents recently launched a renewed offensive targeting the key oil fields and Bentiu is the first major settlement they have retaken.
The White House expressed horror at what it called the "abomination" of spiralling violence in the country, which has left thousands of people dead and forced around a million to flee their homes.
"We are horrified by reports out of South Sudan that fighters aligned with rebel leader Riek Machar massacred hundreds of innocent civilians last week in Bentiu," White House spokesman Jay Carney said.
Images released by the United Nations show piles of bloated, decomposing bodies strewn in several areas - a repeat of mass killings seen elsewhere in the country over the past four months.
The UN said the killings continued for almost two days after the rebels issued a statement boasting of victory in Bentiu, and that the rebels had used hate radio broadcasts to whip up violent ethnic sentiment.
On Wednesday, the US and France called on the UN Security Council to consider sanctions against South Sudan.
The rebels, however, have blamed retreating government troops for the atrocities.
"The government forces and their allies committed these heinous crimes while retreating," rebel spokesman Lul Ruai Koang said.
