Cabinet is today discussing strengthening the process around prisoners sending and receiving letters.
Last week, it was revealed the man accused of the Christchurch terrorist attack sent a letter from Auckland Prison at Paremoremo that later appeared on 4chan.
Corrections officials were aware of the recipients of seven letters he had sent. Two additional were withheld.
Corrections Minister Kelvin Davis read the letter after it was uploaded to 4chan and called its release "unacceptable".
"The letter should not have gotten out - I've expressed that disappointment directly to [corrections]," he said last week.
Today, Mr Davis told 1 NEWS Government was looking at the laws to see if they are fit for purpose.
He said corrections processes were also being analysed to see if they are "up to scratch".
"It would appear that they weren't," he said.
Corrections chief executive Christine Stevenson now has the final say on letters received and sent by the accused terrorist attacker.
On Friday, it was reported another inmate, white supremacist Philip Arps, sent objectionable letters to major news outlets, including TVNZ.