More than 24,000 banned semi-automatic guns - costing taxpayers $45 million - have been handed in since July this year under the amnesty and buy-back scheme.

Photo: RNZ / Ana Tovey

In the past three months, 15,187 firearms owners have been processed, handing in a total of 24,073 firearms and 88,765 parts and accessories.

The buy-back scheme was put in place to allow people to hand in guns that had become illegal under new legislation, prompted by the Christchurch mosque shootings.

Firearms owners have been compensated a total of $45.4million to date. The scheme had been allocated $150 million in the Budget, and that was boosted by an additional $40m from ACC.

Police said the amnesty and buy-back performance data would be published on its website fortnightly.

Deputy Commissioner Mike Clement said the buy-back scheme was unprecedented.

"By reporting this data publicly on a regular basis, firearms owners and the wider community can get a more comprehensive view of how the buy-back scheme is going and what sort of firearms are being taken out of circulation," he said.

He said 68 percent of the firearms handed in were valued at under $10,000 and were categorised in the price list as centrefire semi-automatics.

Other categories handed in include:

Rifles 11+ rounds (valued at under $2000) - 17 percent

Shotgun pump-action, non-detachable magazine, 6+ cartridges (valued at under $5000) - 8 percent

Shotgun semi-automatic, non-detachable magazine, 6+ cartridges (valued at under $5000) - 4 percent

Shotguns with detachable magazines (valued at under $2000) - 3 percent

Photo: RNZ / Dom Thomas

Mr Clement said the attitude of firearms owners who have handed in their firearms has been outstanding but warned others of the deadline.

"Police have collected thousands of semi-automatic firearms and assault rifles during the course of the buy-back so far," he said.

"We are also in contact with E-Cat endorsement holders who own prohibited MSSAs and have yet to comply with the law. The last thing we want to see is law-abiding citizens at risk of facing charges and losing their future firearms licence by failing to comply."

The amnesty and buy-back period ends on 20 December 2019.

"Gun owners have had plenty of notice, plenty of time and plenty of choices. There will be no extension," he said.

Apart from police collection events, there are 38 approved licensed dealers taking bookings for prohibited firearms for hand in.

For those that have 10 or more firearms and/or 50 parts, there are bulk pick-ups available.

For more information go to www.police.govt.nz or call 0800 311 311.