Otto Warmbier, an American university student held prisoner in North Korea for 17 months and said by his family to be in a coma, was medically evacuated to the US on Tuesday as his local church continues to pray for him.

Warmbier, 22, a University of Virginia student from suburban Cincinnati, was detained in January 2016 and sentenced to 15 years of hard labour in March last year for trying to steal an item with a propaganda slogan, according to North Korean media.

Since then, every Sunday the congregation of Ascension and Holy Trinity Church has prayed for him and his family, according to Cincinnati.com.

The pastor, Eric Miller, has yet to meet Warmbier, but some members of his congregation have known him since he was a child.

'We've been praying for him, his parents, and now the people transporting him back home,' Miller said after Warmbier's release. 'It's overwhelming to learn that he's been in a coma for a year,' Miller added. Of Otto's parents, Cynthia and Fred Warmbier, he said: 'I can't even begin to put myself in their shoes.'

He went on: '[Warmbier's imprisonment] has touched people's lives in our church setting. It touches a lot of people in our community in a variety of ways. I think God hears our prayers.'

A member of the congregation, Jenni McCauley said: 'Our entire Wyoming community is thrilled that Otto is finally being returned to the US and to his family. Otto grew up here and we know him as an intelligent, personable, and wonderful young man. At the same time, we are saddened to learn that he is in a coma and we hope that he will soon be returned to full health.'

Warmbier's parents confirmed their son's condition. 'Sadly, he is in a coma and we have been told he has been in that condition since March of 2016,' the parents said in a statement. 'We learned of this only one week ago. We want the world to know how we and our son have been brutalised and terrorised by the pariah regime in North Korea.'

A small group of family friends was nearby to celebrate Warmbier's arrival, cheering and holding signs that read 'Pray for Otto' and 'Welcome home Otto.'

He was placed into an ambulance bound for the University of Cincinnati Medical Center, where a hospital spokeswoman said he would receive treatment.

Warmbier's family said they were told by North Korean officials, through contacts with American envoys, that Warmbier fell ill from botulism some time after his March 2016 trial and lapsed into a coma after taking a sleeping pill, the Washington Post reported.

The New York Times quoted a senior US official as saying Washington recently received intelligence reports that Warmbier had been repeatedly beaten in custody.

Hours after his release, the US government blamed Pyongyang for cyber attacks stretching back to 2009 and warned more were likely.

Warmbier was an award-winning football player and his coach, Steve Thomas encouraged prayers. 'The only comment I have is that I am very happy that he is on his way home and to encourage folks to continue to pray for Otto and his family,' Thomas said. 'The journey for them has been very difficult, to say the least, and they still need our support and love.'

Additional reporting by Reuters.