North Korea's highest court has sentenced an American tourist who allegedly attempted to steal a propaganda banner from a restricted area of his hotel to 15 years of hard labor in prison.

Otto Warmbier, a 21-year-old University of Virginia undergraduate student, was convicted and sentenced in a one-hour trial Wednesday morning at the North's Supreme Court. He was charged with subversion.

No further details were immediately available.

Warmbier was arrested in early January as he tried to leave the country after visiting as a tourist with a New Year's tour group.

In a statement made before his trial, he told a gathering of reporters in Pyongyang he wanted the banner "as a trophy" for the mother of a friend.