US student Otto Warmbier in a coma as he is released from North Korea jail

A US student jailed in North Korea is in a coma after being released from custody, his parents say.

Otto Warmbier, 22, was sentenced to 15 years in prison with hard labour in March 2016 after admitting he tried to steal a propaganda banner.

US Secretary of State Rex Tillerson said the release was secured "at the direction of the President", adding that Mr Warm bier was "en route to the US where he will be reunited with his family".

The 22-year-old was medically evacuated from North Korea, the Washington Post reported.

Image:Mr Warmbier broke down as he was jailed in March 2016

Citing privacy concerns, Mr Tillerson said he would not comment on Mr Warmbier's condition.

However, he noted that the State Department is continuing "to have discussions" with North Korea about the release of other three American citizens who are jailed there.

Mr Warmbier's release came during the first day of a visit to North Korea by former NBA star Dennis Rodman, who said he was "trying to open a door" to the reclusive state.