Police say they've taken a risk-based approach in going through firearms licenses granted around the same time as the Christchurch terrorist.

The agency's been forced to apologise today after the Christchurch mosques attack inquiry found Police failed in its administration of the gun licensing system.

The mosque shooter used his gaming friend, and and his gaming friend's parent as a referee, because his sister couldn't be spoken to in person.

Brenton Tarrant received his firearms licence in December 2017.

Police Commissioner Andrew Coster told Heather du Plessis-Allan they failed to recognise the inadequacy of the referees.

"That is not something we see primarily as the fault of any individual, it was actually about the accuracy of the forms we were using in this process and also the training that we provided."

Coster is urging people to reach out if they have concerns about a firearms holder.

"Information that we have received where there have been concerns about an individual in terms of their suitability to hold a license, we have drilled in on that, but that is an active and ongoing process."

That's despite the Royal Commission inquiry's finding Government agencies knew nothing about the attack, until the manifesto was sent just eight minutes before the shooting.

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