US student Otto Warmbier, who was imprisoned in North Korea for 17 months before being returned home in a coma last week, has died in hospital.

“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 family said in a statement on Tuesday morning (AEST) following Mr Warmbier’s death at the University of Cincinnati Medical Centre.

Mr Warmbier had been in a coma since March 2016, shortly after he was sentenced to 15 years hard labour in North Korea after he tearfully confessed he had tried to steal a propaganda banner.

The family members said they were choosing to focus on the time they were given with their “warm, engaging, brilliant” son instead of focusing on what they had lost.

North Korean officials reportedly told Mr Warmbier’s family on his release on Wednesday that he had been unconscious since contracting botulism and being treated with a sleeping pill.

Doctors say Mr Warmbier had no trace of botulism in his system, but has a severe brain injury and was in a state of “unresponsive wakefulness”.

President Donald Trump described North Korea “brutal regime” in condemning Mr Warmbier’s death.

“Lot of bad things happened, but at least we got him home to be with his parents,” President Trump said before a White House meeting with technology CEOs.

“It’s a brutal regime and we’ll be able to handle it,” he added.

Mr Trump also retweeted a post from his son, Donald Trump Jr, quoting Mr Warmbier’s father criticising the Obama administration for failing to act fast enough to bring his son home.

Dr Daniel Kanter, medical director of the neuroscience intensive care unit at the University of Cincinnati said Mr Warmbier had suffered “extensive loss of brain tissue in all regions of the brain”.

Since returning to the US, Dr Kanter said Mr Warmbier was unable to speak and showed no sign of “understanding language, responding to verbal commands or awareness of his surrounding”.

Last Thursday, North Korea said that it had released Mr Warmbier “on humanitarian grounds”. 

Melania and I offer our deepest condolences to the family of Otto Warmbier. Full statement: https://t.co/8kmcA6YtFD pic.twitter.com/EhrP4BiJeB

— Donald J. Trump (@realDonaldTrump) June 19, 2017

In an official statement released by the White House, the President offered his “deepest condolences” to Mr Warmbier’s family.

“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,” Mr Trump said.

“The United States once again condemns the brutality of the North Korean regime as we mourn its latest victim.”

Senior congressmen referred to Mr Warmbier’s death as “murder” and said the U.S. should respond forcefully.

“Let us state the facts plainly. Otto Warmbier, an American citizen, was murdered by the Kim Jong-un regime,” said Republican Senator John McCain.

Senator McCain said North Korea was threatening its neighbours, had destabilised the Asia-Pacific region, and was trying to develop nuclear weapons capable if reaching the US.

“Now it has escalated to brutalising Americans, including three other citizens currently imprisoned in North Korea,” he said.

“The United States of America cannot, and should not, tolerate the murder of its citizens by hostile powers.”

Fred Warmbier last week told a news conference that when Otto was first arrested, his family was advised by the Obama administration to take a low profile while they worked to obtain his release.

“We did so without result,” he said.

“Earlier this year, [Otto’s mother] Cindy and I decided the time for strategic patience was over.”

Three Americans remain held in North Korea. The US government accuses North Korea of using such detainees as political pawns. North Korea accuses Washington and South Korea of sending spies to overthrow its government.

– With agencies