The 22-year-old US university student who was held prisoner in North Korea for more than a year before being returned in comatose condition died Monday, his family said.

"It is our sad duty to report that our son, Otto Warmbier, has completed his journey home. Surrounded by his loving family, Otto died today at 2:20 pm," the family said in a statement.

"It would be easy at a moment like this to focus on all that we lost - future time that won't be spent with a warm, engaging, brilliant young man whose curiosity and enthusiasm for life knew no bounds. But we choose to focus on the time we were given to be with this remarkable person", Fred and Cindy Warmbier, Otto's parents, wrote.

The Warmbiers thanked the doctors at the Cincinnati hospital where Warmbier was admitted on June 13 for doing everything possible to save his life after he had been turned over in a coma with serious brain injuries by North Korean authorities.

"Unfortunately, the awful torturous mistreatment our son received at the hands of the North Koreans ensured that no other outcome was possible beyond the sad one we experienced today," the student's family said.

The parents said that when their son arrived in Ohio he was unable to speak or respond to stimuli, but the "anguished" look on his face changed the day after his arrival and he seemed to be "at peace."

Meanwhile, President Donald Trump on Monday sent his "deepest condolences" to Warmbier's family, saying that "Otto's fate deepens my administration's determination to prevent such tragedies from befalling innocent people at the hands of regimes that do not respect the rule of law or basic human decency."

"The United States once again condemns the brutality of the North Korean regime as we mourn its latest victim," the president added.

US Secretary of State Rex Tillerson announced last week that his department had managed to secure the young man's release.

Warmbier spent more than a year in a coma, which he slipped into shortly after his last appearance in public during his March 2016 show trial for allegedly stealing a propaganda poster while on a student visit to Pyongyang, his family said.

The North Korean regime claims that Warmbier suffered an attack of botulism and was given a sleeping pill by his captors, but he fell into a coma, a narrative that the family has refuted.