Police Minister Stuart Nash blocked a National MP from visiting a police station - because he wanted to see it first.

Chris Bishop is livid that his trip to see a family violence pilot in Christchurch was canned 45 minutes before he was due to arrive. Embarrassed police told him it was at the behest of their Minister.

The Hutt South MP, who is also National's police spokesman, says it's "pretty paranoid behaviour".

But Nash is unapologetic, arguing it's a long-standing protocol that MPs "seek endorsement" to visit police stations outside of their electorate. "Mr Bishop knows about the usual protocols," he said.

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JARRED WILLIAMSON/STUFF Police Minister Stuart Nash says MPs must request permission from him to visit police stations outside their electorate.

The rivals have recently clashed over police numbers and the controversial promotion of top cop Wally Haumaha.

Nash's intervention happened in July, but has flared up now because Bishop was infuriated by comments made this week in Parliament.

Nash had said: "I just do hope that we can work together as a Parliament to do something about the scourge that is domestic violence... if those from the Opposition parties are keen to participate in a meaningful and constructive way, then we will absolutely welcome—welcome—their input."

Bishop accused Nash of hypocrisy. "It's pretty galling to turn up to the House, invite us to work with him, only a couple of months after he stopped me visiting an initiative that we established, on the grounds he hadn't been there yet."

He says he first approached the police in April about visiting the Integrated Safety Response scheme, which was set up under National.

Ross Giblin Police Minister Stuart Nash has clashed frequently with Chris Bishop in Parliament.

In late June he exchanged emails with the ISR team, and confirmed a visit on July 2, when he was in the city for a justice select committee hearing. They even sent him directions and offered a car parking space.

But 45 minutes before he was due to arrive, his office got a call "apologising profusely, and stating that she has been requested by the Minister of Police's office to cancel the engagement since he has not had a chance to visit the premises himself."

"It was a waste of an afternoon, I had to cool my heels at the airport. It's not how politics should be done, basically and it's pretty rude.

"I wasn't going there to embarrass him, I was going down there to check out a initiative that we in the National party are proud of."

Bishop wasn't aware of the protocol Nash has set out. "I'm not sure there is a convention. Opposition MPs should be able to engage with police stations - it's a really important part of the role, getting out and about and seeing programmes that are working and meeting police."

Nash says Bishop approached local police and he then declined to approve the visit "following confirmation that Mr Bishop had not lodged the request through the Minister's office."

"This protocol has been in place under successive governments...Mr Bishop is welcome to seek endorsement to visit the ISR pilot site ahead of his next visit to Christchurch or Hamilton. Police informed the Minister that they would find a suitable date for Mr Bishop to make a site visit."

Nash confirmed he visited the ISR team on August 10.

Nash disputes the cancellation was because he was yet to visit.

A spokeswoman for Nash said: "[National MP] Tim McIndoe was given the ok to visit the ISR [in Hamilton] in July while the Minister visited in August so clearly the chronology was not an issue."

Bishop says he's still keen to visit. "I'll be in touch with Mr Nash's office to arrange it," he said.