SEOUL, South Korea (AP) — North Korea on Friday denied it cruelly treated or tortured an American student who was detained for more than year and died days after being released in a coma.

The comments published by the official Korean Central News Agency were North Korea's first reaction to Otto Warmbier's death in a U.S. hospital on Monday after it released him for what it called humanitarian reasons.

Doctors at the hospital said Warmbier had suffered a severe neurological injury from an unknown cause. Relatives say they were told the 22-year-old University of Virginia student had been in a coma since shortly after he was sentenced to 15 years of hard labor in North Korea in March 2016.

His family and others have blamed North Korea for his condition.

Warmbier was accused of stealing a propaganda poster. KCNA said the North dealt with him according to its domestic laws and international standards.

The article also criticized South Korea for using Warmbier's case to seek the release of other detainees, including six South Korean citizens. South Korean President Moon Jae-in said in an interview with CBS television earlier this week that it was clear North Korea bears a heavy responsibility for Warmbier's death.

"Our related institutions are treating criminals who committed crimes against (our) republic strictly based on domestic law and international standards, and Warmbier was no different," KCNA said.

It accused South Korea of tarnishing North Korea's image with "slanderous talk about cruel treatment and torture" while having no knowledge of the "humanitarian" treatment Warmbier received.

KCNA didn't provide details of how Warmbier was treated or what might have caused him to lapse into a coma.

It demanded that South Korea return 12 restaurant workers who defected to the South last year. South Korea said the women defected on their own, while North Korea claimed they were deceived and abducted to the South.

The United States, South Korea and others often accuse North Korea of using foreign detainees to wrest diplomatic concessions. Three Americans remain in custody in the North.