The government is seeking advice after multiple high-level calls to give the Royal Commission of Inquiry into the Christchurch mosque shootings more time to complete its investigation.
The Royal Commission, as well as the Muslim group set up to assist it and the Federation of Islamic Associations, have all asked the government for an extension.
Some say the current timeline is "unrealistic" and severely undermines the "complexity and gravitas" of the investigation.
Just ten days after the shootings, the prime minister announced a Royal Commission would investigate, in short, what could or should have been done to prevent the attacks on 15 March. It would also look at what could be done to prevent similar attacks in future.
The government appointed two commissioners and gave them eight months to investigate. But now, six months into the inquiry, the government has been told that's not enough time.
In a letter obtained by RNZ, the Muslim Community Reference Group told the government in September the timeline was unrealistic and restricting.
"We believe the government has provided an unrealistic timeframe for the Royal Commission to report on the terrorist attacks of 15 March and this has severely undermined the complexity and gravitas of the task on hand.
"The current timeframe restricts the Royal Commission in delivering a comprehensive report by 10 December 2019."
Some members of their community are only now ready to engage with the inquiry, the letter said.
The December deadline didn't factor in such matters as the grieving period and the focus on Ramadan and the Hajj season, it said.
"We need to also consider cultural sensitivities and language barriers which can prolong the consultation process.
"This is a once in a lifetime opportunity for reform in this country and we will only get this if the commission has time to consult the Muslim community appropriately on specific concerns and recommendations."
In the letter, the group said the inquiry has made some progress in engaging with parts of the community, but it has more to do before it can deliver an adequate report.
The group said it is helping the Royal Commission connect with Muslim and other ethnic communities affected by white supremacy and xenophobia.
But, it said for this to be done, they need an extension.
"The Royal Commission will not adequately serve its purpose if the report does not have integrity in the eyes of the primary communities impacted by the attacks."
The head of the Federation of Islamic Associations is backing the calls for an extension.
Mustafa Farouk said the commission has done a good job of engaging with the Muslim community, but there are many more who would like to be a part of the process.
"We want to give our community enough time to give input into the commission of inquiry ... we need more time to do a good job about it."
He said extending the timeline would mean that everyone who wanted to contribute would be able to.
The minister responsible for the Royal Commission, Tracey Martin, was not willing to be interviewed but in a statement said she has heard similar concerns from the inquiry itself and the Federation of Islamic Associations.
"Any proposed change to the Royal Commission's terms of reference, including timeframes, will need to be considered by Cabinet and approved by the Governor-General.
"At this stage, I have asked my officials to engage with the Royal Commission and provide me with further advice."
The Royal Commission of Inquiry said in a statement it has written to Tracey Martin regarding the timeframe of the inquiry.
It said questions about the timeframe have also been raised at meetings with the Muslim Community Reference Group.