SEOUL, June 20 (Xinhua) -- South Korean President Moon Jae-in on Tuesday sent a consolation letter to the family of the late U.S. student who died days after his release from the Democratic People's Republic of Korea (DPRK).

Moon's spokesman Park Soo-hyun told a press briefing that the president has sent the letter to the family of Otto Warmbier, 22, who was held prisoner in the DPRK while traveling, to console the bereaved family.

In the letter, Moon expressed regrets for the U.S. university student's death, conveying his words of deep condolence and consolation, according to the spokesman.

Warmbier, the University of Virginia student, was arrested in the DPRK in January 2016 for trying to steal an item showing a propaganda slogan, and was sentenced to 15 years of hard labor in March in the year.

Following a series of diplomatic contacts with the United States, the DPRK released him in a coma.

The president urged Pyongyang to return other South Korean and U.S. citizens held by the DPRK, vowing to make all-out efforts to their release.

Moon's comments came ahead of his scheduled visit to Washington later this month for his first two-day summit meeting with U.S. President Donald Trump from June 29.