Trump 'old lunatic' says North Korea

North Korea's foreign ministry has described US President Donald Trump as an "old lunatic", saying he was exploiting the death of Otto Warmbier - an American student who died a week after returning to the US from captivity in a North Korean prison.

Warmbier was arrested after he tried to steal a propaganda sign from a hotel in North Korea.

Pyongyang accused the US of pushing Otto into breaking the law.

"Trump and his clique, for their anti-DPRK propaganda, are again exploiting the death of Otto Warmbier, an American college student who had been under reform through labour for the criminal act he committed against the DPRK and died after returning to the US," read the statement from North Korea's foreign ministry on Thursday.

The comments came shortly after a county coroner in the US state of Ohio found Warmbier had died from a lack of oxygen to the brain, which seemed to contradict statements made by the student's parents in an interview with Fox on Tuesday.

They said North Korea had "systematically tortured" their son.

Otto died only a week after returning to the US on 13 June, having spent 17 months in captivity in North Korea.

On his return, he was in a coma with severe brain damage, and could not communicate.