Firearms owners in Nelson, Hawke's Bay and Canterbury staged protests on Saturday as part of a national demonstration over the gun buy back scheme.

They were also drawing attention to a data breach where an external software developer, German company SAP, updated the system in a way which hadn't been authorised by police.

Police have confirmed the full details for 35 people had been accessed by one dealer, including name, address, contact number, firearms licence number and bank account details.

LUZ ZUNIGA Firearms owners also protested in front of Nelson Courthouse in opposition to restrictions imposed after the Christchurch attacks.

About 20 protesters stood silently with placards opposite the Christchurch Central Police Station from 10am to midday on Saturday.

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The group of Council of Licensed Firearms Owners (Colfo) members were there to express their concerns about the data breach, which they said had put gun owners at risk, spokesman Sam Kircher said.

CHRIS SKELTON/STUFF A small group of people gathered outside the police station in central Christchurch to protest against a recent data breach and gun law reforms.

"People are frightened for their lives."

Kircher said the breach highlighted the problems and risks that would result from a gun owners registry, one of the proposals in the second tranche of gun law reform proposals under consideration by the Government.

Gun Control New Zealand spokesman Nik Green said any data breach was unacceptable but it didn't mean a register should not be adopted.

"Lots of countries have gun registers, they don't have widespread theft so it is clearly possible to make registers work in a way that protects people's privacy."

Outside Nelson Courthouse, local protest organiser Blair Jones said while a similar protest outside the opening of an Auckland school by Prime Minister Jacinda Ardern was a good opportunity for protesters to make their presence felt, the top of the south event was as much about encouraging others to be involved as it was about making their voice heard.

"There's heaps of walks of life here but we've all got the one common goal - that's to fight for our democratic rights to be addressed."

"It's just a shame we haven't done anything sooner - we've sort of kicked into gear with trying to bring everyone together with a common front to voice our concerns, because we're not being heard.

"No one's yelling and yahooing - it's peaceful and everyone's just getting to know each other."

Jones said many gun owners felt "like scapegoats" throughout the gun reform process and had battled the stigma of being "gun nuts" while trying to defend their stance on gun ownership.

"Having other New Zealanders give you that persona is really distressing and then to have that line in the sand drawn by the police and the Government.

"We're sort of targeted to be the crowd that everyone should be scared of - and that's absolutely disgusting.

"It's a big worry for our group about what's going to come next with all the laws."

"It always comes back to Christchurch thing - (the gunman) got his licence within five weeks, the question gets asked why he was able to do that - no answers....why was he able to to get 2500 rounds so soon after he got his licence - no answer ...it's the police environment that gave him his licence, not us."