The mosque terrorist claims prison conditions essentially forced him to plead guilty to his crimes.

The shooter has addressed three Court of Appeal judges in Wellington in a bid to vacate his guilty pleas for murder, attempted murder, and terrorism - in March 2019.

He's serving life in prison.

Newstalk ZB's Emily Ansell says Tarrant told the court solitary confinement, being under constant observation and the lack of reading materials helped his health decline.

"He also mentioned he thought guards were playing mind games with him and telling him they couldn't understand what he was saying. So all of this, he says, led to something of an identity crisis."

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