North Korean officials say they will indict an American who was reportedly doing missionary work in the country.

A South Korean newspaper reports authorities arrested a man in his 60s, identified as Jun Young-Su, in November. He admitted to committing a crime against the nation but North Korean officials have not said what that crime is.

The paper says the Korean-American businessman from Orange County, Calif., is being investigated "for committing a crime against the DPRK (North Korea) after entering it. He admitted his crime in the course of investigation." 

South Korean media reports Jun was arrested for "spreading Christianity." There's been no word on what kind of religious activity Jun was involved in.

Meanwhile, U.S. State Department spokesman Mark Toner called on North Korea to "release this citizen on humanitarian grounds," and "treat this citizen in a manner consistent with international human rights law."

Citing the Privacy Act, Toner declined to elaborate on the identity of the citizen or for what they were being detained.