Invercargill Mayor Sir Tim Shadbolt and his deputy Nobby Clark haven't spoken in person in weeks, with the deputy mayor admitting the relationship is strained.

The latest ructions around the council table centre on Shadbolt's driver's licence.

Media queries on why Shadbolt was not behind the wheel of the mayoral car led to Clark asking the mayor to be transparent and tell the public what was going on.

Instead, the mayor's Facebook page posted a news story about the matter alongside the commentary: "My most current 'Et tu Brute' moment. Beware the Ides of May (sic) or as in my case - councillors who whisper to the press".

It had since emerged Shadbolt's driver's licence was suspended, though it was not known why and Clark believed the mayor should simply tell the public so the matter could be put to bed and attention turned to more pressing matters.

"It's not a big issue but I guess it's probably part of a wider issue the media are interested about - his overall performance - and I just think there's more important things to focus on and so I did ask him to consider doing it," Clark told RNZ.

"I wasn't particularly interested for the reasons why. But he's refused that. He just says it's personal and every time I've asked he's just said 'You need to talk to my lawyer'."

Clark was the third deputy mayor of the city in as many years after his predecessor, Toni Biddle, stepped down in October citing the toxic culture around the council table.

Her predecessor, Rebecca Amundsen, was not chosen for the role following 2019's elections after she stood against Shadbolt for the mayoralty.

An independent review, released last year, found most of the council's tensions stemmed from a leadership void, with Shadbolt increasingly unable to carry out duties.

The mayor dismissed the findings immediately - saying he was a scapegoat.

Clark said that response was unexpected and "pretty disappointing".

"There were things in there that were pretty cutting towards him, as there were for me and [Invercargill City Council chief executive] Clare [Hadley]. Now I could've jumped up and down and said 'I don't believe anything that's in here, I think it's a one-sided story', but there's nothing to be gained by that. You've just got to work forward, not look backwards.

"The mayor at a formal meeting adopted the Thomson report - he was the one who moved the recommendations, I seconded it. So that was strong statement to the councillors and the council staff that we were both committed to going forward.

"A couple of days later we had a gathering of the press and the chief executive, myself and Tim were to present a united front to that. Clare spoke first and then out of left-field the mayor basically just trashed the report and said he didn't agree with it. So that was very disappointing and deflated a lot of councillors. We've struggled with that ever since."

Clark said councillors and the council's executive had stepped up their game since the review, however, Shadbolt's leadership had not improved.

"It's a little bit like trying to row a waka and you've got one member rowing in the opposite direction," he said.

Clark was adamant none of what he was saying was driven by politics and he had no intention of standing for council, let alone the mayoralty, at next October's local body elections.

"I've said I'll stand for the challenge of doing that for the next 16 or 17 months until the next election because I think the city deserves that. They don't deserve another deputy that either resigns or withdraws from being deputy - that just shows a further level of dysfunction. So I'm committed to seeing out that time but it's not something I do with much glee at the moment because it's just hard work and consumes you in some ways."

His time as deputy mayor had contributed to that decision, he said.

Clark said he was open to mending the relationship with Shadbolt, but there was no easy fix.

"You've got to understand it's not just me and the mayor - there's a partner that plays an important role as well and so that's the hard part. I think if it was just Tim and I sitting in a room with a beer we'd sort this out, but there are other factors at play here."

It was "weeks ago" that the pair spoke person-to-person, Clark said.

"It's strained," he said, when asked if the relationship had broken down.

RNZ approached Shadbolt, but he did not return calls.