Hawzah News Agency - (Auckland - New Zealand) - Officials in New Zealand apologized Thursday after the alleged Christchurch mosque gunman was allowed to send a letter from prison espousing 'hateful' views that a supporter then shared online.

Australian Brenton Tarrant is in a maximum-security jail in Auckland awaiting trial for the murder of 51 Muslim worshipers on March 15 in the worst mass shooting in modern New Zealand history.

One of the letters from the self-avowed white supremacist, addressed to a Russian man named Alan, was posted to the website 4Chan.

Handwritten in block letters, the six-page note discusses a trip Tarrant made to Russia in 2015, his admiration for British fascist Oswald Mosley and his belief "there is a great conflict on the horizon".

Prime Minister Jacinda Ardern, who has vowed never to mention Tarrant by name, was furious the letter had bypassed the correction department's vetting system.

"Corrections themselves have acknowledged the failing here... this individual should not be able to share his hateful message from behind prison doors," she told reporters in Tuvalu, where she is attending a regional summit.

Corrections Department chief executive Christine Stevenson said the letter should never have been sent.

"I would like to apologize for the distress that this has caused to those impacted by the tragic events of 15 March," she said.