SEOUL, South Korea (AP) — North Korea said Thursday it released an American university student over "humanitarian" reasons in its first official comment since he was returned to his home state of Ohio in a coma.

The state-run Korean Central News Agency said Otto Warmbier had been serving hard labor but didn't comment on his medical condition or how the country negotiated his release with the United States.

"Warmbier, who had been in hard labor, was sent back home on June 13, 2017, on humanitarian grounds according to the adjudication made on the same day by the Central Court of the DPRK," the agency said in the one-sentence report, referring to North Korea by its official name, the Democratic People's Republic of Korea.

The 22-year-old Warmbier, a University of Virginia undergraduate, was convicted and sentenced in a one-hour trial in North Korea's Supreme Court in March 2016. He got 15 years in prison with hard labor for subversion after he tearfully confessed that he had tried to steal a propaganda banner.

He was medically evacuated from North Korea and arrived in Cincinnati late Tuesday. His father, Fred Warmbier, told Fox News that his son was "terrorized and brutalized" and has been in a coma for more than a year.

The U.S., South Korea and others often accuse North Korea of using foreign detainees to wrest diplomatic concessions. Three Americans remain in custody in North Korea over accusations including alleged "hostile acts" and spying.