A U.N. report says the "lawless" activities of South Sudan's national security and military intelligence risk turning the war-torn country into a police state run on fear and corruption.

The report published Wednesday by the U.N. Commission on Human Rights in South Sudan said the increasing securitization of the state threatens citizens' rights as the country emerges from five years of civil war, which killed almost 400,000 people and displaced millions.

The report, based on 135 witness statements and over 3,000 documents including confidential records, said South Sudan's challenges moving forward are "immense," compounded by the protracted conflict, deep ethnic divisions, an economic crisis and a "dysfunctional and predatory elite system of government."