Christopher Luxon says it would be "disingenuous" to say a photo circulating online of National MP Tama Potaka posing with gang members is the same as images of Labour, Green and Te Pāti Māori MPs.

Labour candidate for Tamaki Makaurau, Kerrin Leoni, resigned on Friday after video and an image of her campaigning in party attire, and posing with Mongrel Mob members at a fundraising event were published online.

Initially Labour leader Chris Hipkins had backed Leoni saying she was at a family event with some of her whanau who are gang members.

But after a video circulated online on Thursday night Hipkins said it became untenable for Leoni to stay on as a candidate as she had not provided the full story of what had happened.

Earlier this month Hipkins had distanced himself from Green and Te Pāti Māori MPs and candidates who had attended an election hui at a gang pad and posed for photos with mongrel mob members.

On Saturday Luxon was asked whether he was aware of any images of his MPs or candidates posing with gang members and whether he would consider that acceptable given his tough criticism of opposition MPs and candidates.

Luxon said he hadn't seen any images himself but was aware one was doing the rounds of MP and Māori Development Minister Tama Potaka.

"He's not campaigning, he's not fundraising, he's not raising funds for the mongrel mob," Luxon told reporters.

"And go talk to Tama - he's very much against gangs, like the rest of us in the National Party."

"I think it'd be disingenuous to suggest that they are equivalent images that we've seen."

Luxon suggested media speak to Potaka, saying, "you'll get a very clear view from him about what's happened around crime and law and order".

"He represents an area in Hamilton that was very challenged…he understands the suffering that people have gone through, and he doesn't think gangs are good for society."

While Luxon hadn't spoken to Potaka about the photo or its origins, National MP and Police Minister Mark Mitchell had.

Mitchell was at Saturday's media conference with Luxon and asked to speak to the issue.

"Tama was at an event three years ago, it was at the Kiingitanga for an event there when that photo was taken.

"He wasn't campaigning. He wasn't engaging gang members to ask them to get organised to vote for the National Party - in fact, he was probably getting a hard time because we were implementing our gang legislation," Mitchell told reporters.

"There is a big difference between being at a public event and attending a public event and having gang members approach you. I've had gang members approach me at public events.

"There's a big difference between that and fronting up to a gang fundraiser or a gang pad to try and ingratiate yourself with those gang members to actively campaign and try and get them to campaign and vote against a government that has made this country much safer, that has made it much harder to be a gang member in our country, and we will continue to do that," Mitchell said.

On why Potaka posed for the photo Mitchell speculated that he was trying to be "respectful and not create a scene".

"We get thousands of photos every day of people in a public place. We don't know every individual. We don't know their background. We don't know their history. That's just the nature of public life.

"There is a huge difference between that and actively going to a gang pad or a or a function organised by the gangs, a fundraiser by the rogue chapter that's very well known for violence and for peddling meth, and going along there in your party attire with your signage, standing up and actively campaigning, there is a huge difference, and I think the public can work that out very quickly," Mitchell said.