JUBA - Nearly 900 South Sudanese died during a burst of violence between rival cattle herding tribes in late 2011 and early 2012, the United Nations said on Monday, criticizing the newly formed state's army for failing to protect civilians.

South Sudan, which split away from Sudan a year ago, has been struggling to stamp its authority on an undeveloped country the size of France awash with weapons.

In one of the bloodiest episodes since independence, an estimated 7,000 heavily armed youths from the Lou Nuer tribe attacked villages belonging to the rival Murle in eastern Jonglei state at the end of last year, stealing tens of thousands of cattle and abducting women and children.

The onslaught forced tens of thousands of people to flee their homes, killed 612 people and triggered a wave of revenge attacks in which another 276 died, the United Nations said.

Please LIKE our Facebook page - it makes us stronger