US President Donald Trump has slammed the incarceration and eventual death of 22-year-old Otto Warmbier as "a total disgrace".
"The smear campaign against (North Korea) staged in the US compels us to make firm determination that humanitarianism and benevolence for the enemy are a taboo and we should further sharpen the blade of law," the foreign ministry spokesman said in state media.
The North had earlier Friday denied torturing or mistreating Mr Warmbier, in the first official reaction to his death.
"Our relevant agencies treat all criminals... thoroughly in accordance with domestic laws and international standards and Warmbier was not an exception," a spokesman for the National Reconciliation Council said.
"Those who have absolutely no idea about how well we treated Warmbier under humanitarian conditions dare to utter 'mistreatment' and 'torture'," he said according to the official KCNA news agency.
Mr Warmbier was buried Thursday in Ohio, less than a week after he was sent back home in a mysterious coma.
He had been incarcerated for more than a year in North Korea after allegedly stealing a political slogan while on a trip to the capital Pyongyang as a tourist.
