New Zealand Prime Minister Jacinda Ardern on Monday vowed accountability for the families of last year's Christchurch mosque attack victims, ahead of the public release of a major report on the country's worst massacre.

White supremacist Brenton Tarrant was sentenced to life in prison without parole in August for killing 51 Muslim worshippers and injuring dozens of others at two mosques in the South Island city on March 15, 2019.

The findings of a royal commission inquiry into the attack will be made public in Parliament on Tuesday. The inquiry was formed to look at whether there were any failings by government agencies and if the mass shooting could have been prevented.

"I absolutely appreciate the (Muslim) community will want to see accountability in terms of implementation. They will want to see who is responsible for coordinating some of those efforts ... and we will be providing that," Ardern told a regular media briefing, according to Reuters.

The 792-page report took about 18 months to finish and contains interviews with hundreds of people including security agencies, Muslim community leaders, international experts and officials in England, Norway and Australia, along with Ardern.

"We wanted to ensure that if there were any failings by government agencies – if there was anything that could have been done to prevent the attacks – that we identified them and that we learned from them," she said, adding that the "very comprehensive" report makes recommendations across a number of areas, and it may take some time to implement all of the findings.

Ardern received global praise for her compassionate response to the attack and for swiftly banning the sale of the high-capacity semiautomatic weapons used in the attack. She also launched a global movement against online extremism.

However, authorities were criticized for ignoring repeated warnings from the Muslim community that they were experiencing an escalation in hate crimes. Critics also said security agencies failed to record hate crimes and ignored the growing threat from white supremacists.

Ardern met with the family members of victims and some survivors on Sunday and promised immediate action on the royal commission report but said some recommendations may take time to implement.