The accused Christchurch mosque gunman has been able to send seven letters from prison.
Corrections Minister Kelvin Davis told RNZ the accused gunman sent seven letters.
Two were to his mother and five to others. Davis did not know the identity of those who received the remaining letters.
He believed the accused had received a "couple of dozen" letters from around the world.
Corrections had made a mistake and a letter sent to an admirer, revealed this week, should have been withheld, Davis told Newstalk ZB's Mike Hosking this morning.
"I've expressed my disappointment to them. They have apologised to me, but more importantly for the distress it's caused to a large sector of our community.
"They need to own it, they need to make sure it doesn't happen again."
The Corrections Department has conceded the accused gunman should not have been allowed to send a letter to an admirer which was posted on a website earlier this week.
He wrote about his political and social views, but said he cannot go into great detail about his regrets or feelings "as the guards will confiscate my letter if I do (to use as evidence)".
Hosking asked Davis whether a "call to arms" in part of the inmate's letter should have alerted Corrections that the letter should be withheld.
But Davis said the "call to arms" was a matter of interpretation.
The normal process was for Corrections to deal with mail that detailed overt actions.
New Zealand had never dealt with a prisoner like this before, Davis said.
"I've asked the question, are our laws as they stand actually fit for purpose?"
He had asked for advice on changes they may need to make, Davis said.
"The safety of the public of New Zealand and internationally is our number one priority."
New Zealanders would be surprised that prisoners were entitled to send and receive mail, but there were limited circumstances where it could be withheld, Davis said.
"Corrections has put a temporary stop on this prisoner's mail until we... receive absolute assurance that it upholds the safety of the public."
Corrections chief executive Christine Stevenson was very competent and should not resign, Davis said. She had apologised for Corrections' failing over the letter.
Corrections boss apologises
The accused gunman would be blocked from sending or receiving mail pending a review, Corrections' chief executive Christine Stevenson said last night.
Prime Minister Jacinda Ardern said the alleged Christchurch gunman should not have been able to send a letter expressing what she called his "hateful views" from behind bars.
Stevenson apologised in a statement last night.
"I would like to apologise for the distress that this has caused to those impacted by the tragic events of 15 March," she said.
"We have taken swift action to ensure that our processes are as effective as we need them to be. With immediate effect, this prisoner will not be able to send or receive any mail until we have absolute assurance that the process in place for screening and assessing his correspondence upholds the safety of the public, both in New Zealand and internationally."
The accused gunman had been in custody for five months, Stevenson said.
"It is a fine balance to uphold our lawful obligations and mitigate all potential risks posed by the prisoner, however we are absolutely committed to ensuring that he has no opportunity to cause harm or distress, either directly or indirectly."