U.S. President Donald Trump on Friday said the United States did not pay any money to North Korea as it sought the release of Otto Warmbier, a day after a report said Trump had approved a $2 million bill from Pyongyang for the American student's care.

"No money was paid to North Korea for Otto Warmbier, not two Million Dollars, not anything else," Trump wrote in a tweet.

The Washington Post reported on Thursday that Trump had approved payment of a $2 million bill from Pyongyang to cover its care of the comatose college student, who was held in a North Korean prison for 17 months until June 2017.