Police Commissioner Mike Bush appeared before the Justice Select Committee and spoke about gangs with firearms and the gun buyback scheme.

Illegal guns are remaining in the hands of organised crime as gang leaders refuse to give up their weapons.

Police have met with more than 50 gang leaders in an effort to get them to comply with firearm law changes before an amnesty ends.

But it's proving to be fruitless, as the patched members remain "very reluctant", Police Commissioner Mike Bush told the Justice Select Committee on Thursday.

"We have identified over 100 influential gang leaders and spoken to about half of them about how they are managing this and what their approach and attitude toward that [amnesty] is."

After the committee meeting, Bush said communication lines with senior patched gang members had revealed they had a different approach to law abiding members of the public, in relation to the return of guns.

COLLETTE DEVLIN/STUFF Police Commissioner Mike Bush and Deputy Commissioner Mike Clement told the Justice Select Committee 115 key gang members had been identified and police had met with 53, to talk about guns.

"They were very reluctant to be part of this."

He did not think many patched gang members had handed in their guns.

Police already had a strategy for dealing with gangs and that is what police were using to get to the unlawful firearms, he said.

"They are in the hands of people involved in organised crime."

During organised crime interventions, police located a lot of unlawful firearms, he said.

"If people are in possession of an unlawful firearm this very minute and we know about it, we will be taking the approach we have always taken … we have information, we will be going there."

Deputy Commissioner Mike Clement told the committee that out of the 37 adult gangs across the country, 115 key people had been identified and police had met with 53 to talk.

Police did not expect patched gang members to front up to collections but were hopeful they would listen and do the right thing, Clement said.

But at the end of the day, police could not compel them to give up their unlawful guns and could only create an environment to hand over firearms under amnesty, he said.

After the meeting, National's Justice spokesperson and former police officer Mark Mitchell said asking gangs nicely to give up illegal weapons didn't work.

"The gun buyback scheme ends next month. Police have acknowledged that the gangs haven't been handing in their firearms. Police Minister Stuart Nash has sent out a reminder. He needs to do more than that to get the gangs listening."

STUFF Bush said communication lines with senior patched gang members had revealed they had a different approach to law abiding members of the public, in relation to the return of guns. They were very reluctant to be part of it. (File photo)

FPOs gave frontline police staff the ability to act in real time to search and recover illegal firearms in the possession of gang members, he said.

"We've done all the work and written the Bill. Police Minister Stuart Nash should support it."

It comes after Stuff revealed a flashy new breed of suited gangster had drawn the ire of Police Minister Stuart Nash, who plans to increase police powers to target the criminal kingpins.

He was planning a review of the Crimes Act and proceeds of crime laws, that will go after gang hierarchy and bring a paper on Firearm Prohibition Orders (FPOs) to Cabinet, which aims to keep guns out of the hands of gangs.

COLLETE DEVLIN/STUFF The New Zealand Police Association President Chris Cahill and Police Minister Stuart Nash spoke at the annual conference about the changing face of organised crime and problems with gangs.

During the committee, National's police spokesman Brett Hudson asked Bush about the estimate (60,000 - 173,000) of how many now prohibited firearms were in the country and if he had confidence it was at the 60,000 or lower level.

It follows a report by Stuff that police could struggle to collect even the lowest estimate of banned guns and could fall short before the December 20 deadline. This led Police Minister Stuart Nash to question if there could be fewer guns in the country than experts calculated.

"There is no science or ability to be accurate on the numbers ... we have no way of knowing," Bush said.

Official figures show that between July 13 and October 29 about 32,659 firearms were collected and more than $62 million had been paid out so far.

Police had talked to nearly 20,000 gun owners at more than 330 collection events around the country, and 200 more will be held in the next 50 days, as the end of the six month amnesty and buy-back draws to an end.

There would be no extensions.

"This will be a success because after six months, there would have been ample opportunity for good, honest law-abading people to surrender firearms. I can guarantee that after that six months, we will be entitled to and will be out there looking for the people who didn't comply," Bush said.

Clement told the committee 67 per cent of the firearms bought in the buyback were in the semi-automatic category.