An American student sentenced to 15 years of hard labour in North Korea, has been medically evacuated from the rogue nation in a coma.

It appears Otto Warmbier has been in the coma since March.

READ MORE: US student released by North Korea after 17 months 'in a coma'

US correspondent Richard Arnold told Mike Hosking one story put out by North Korea, is that he contracted botulism while in prison, and was given a sleeping pill that put him into a coma.

"That makes about zero sense. There are other reports that he was beaten. His parents, from Ohio, say they want the world to know that their son has been 'brutalised' and 'terrorised' by the pariah regime" he said.

LISTEN ABOVE AS RICHARD ARNOLD SPEAKS WITH MIKE HOSKING