Nairobi - South Sudan's president will seek election next year, a spokesperson said on Wednesday, in what will be the first vote on Salva Kiir's leadership since the turbulent country won independence.

The president "is a uniting factor. If he leaves power now, the whole country will collapse," spokesperson Ateny Wek Ateny told The Associated Press.

Kiir was elected in 2010, a year before the East African country gained independence from Sudan. Presidential elections set for 2015 were delayed by civil war that began in December 2013 and continues to rage.

The United Nations has warned that South Sudan is witnessing ethnic cleansing and is at risk of genocide.

Tens of thousands of people have been killed, and the United Nations says more than three million people are either internally displaced or living as refugees.

The international community has grown frustrated with Kiir and other South Sudan leaders as the fighting drags on.

In his last remarks as US special envoy before leaving office in January, Donald Booth said the United States "wanted peace for South Sudan far more than its leaders did."

In recent months, power struggles within the government over who might succeed Kiir as president have grown to dangerous levels.

Kiir's rival and former deputy-turned-rebel leader Riek Machar fled the country last year when fighting erupted in the capital, Juba.

South Sudan has been named the second most corrupt country in the world by Transparency International.

The Sentry, a US-based corruption watchdog, has said Kiir and his family have plundered the oil-rich country's natural resources.