A royal commission of inquiry into the terror attacks in Christchurch on Friday could be one of the options considered by the Government.
Speaking to RNZ this morning, Prime Minister Ardern said there was "a couple of considerations" the Government was thinking about in terms of an investigation into the mass shooting.
She did not rule out a royal commission of inquiry.
But she didn't want to pre empt what kind of inquiry will be launched at this stage, as any inquiry would deal with classified information from New Zealand's intelligence agencies.
She will be discussing this with Cabinet today.
"Obviously questions are being asked around was there anything here that should have been flagged with agencies [in terms of] this particular individual."
The man charged with murder after Friday's shooting was not on any security watch lists in New Zealand or Australia.
In the wake of the shooting, Ardern said people have been asking if the Government has been taking the threat of far right-wing, white supremacist extremism seriously.
From the information she has had provided by intelligence agencies, Ardern said the answer to that question is yes.
"In fact over the last nine months specifically, they have been doing more work in that space."
She said the agencies take very seriously any allegations brought to them – "but this still was just not a person who had come to their attention in that regard".
She said the Government needed to give people an independent assurance of that – she said this is something the agencies want too.
"I'll be discussing that with Cabinet today."
Speaking to Newstalk ZB, she said the Government would continue to ask questions about the gunman's overseas travel.
Reports have emerged that the gunman had spent time in Eastern Europe recently.
In fact, in a press conference on Saturday, Ardern said the man's movements coming to and from New Zealand over the years were "sporadic".
"The periods of time here in New Zealand have been of varying lengths, but it's nothing that I would describe as long term or domiciled here by any stretch."
Cabinet will today be discussing new gun regulations and it is expected Ardern will announce a ban on military-style semi-automatic weapons and tighter controls on gun ownership.
Opposition leader Simon Bridges said the National Party would back gun law reform.
Ardern told Newstalk ZB she was prepared for any push back from those who would resist any changes to New Zealand's gun laws.