Installing a commissioner at the embattled Invercargill City Council is the most sensible option, a local government expert says.

The council has come under increasing scrutiny after the Department of Internal Affairs requested information in August over rising tensions and serious concerns about their ability to govern.

It has been undergoing an independent governance review as part of that process, which yesterday revealed long standing mayor Sir Tim Shadbolt was struggling to fulfill significant parts of his role, leaving behind a leadership void.

Dr Andy Asquith is keenly following the debacle at Invercargill City Council - he is the director of the Public Sector Management Group at Massey University.

For him, setting up a commissioner made the most sense - but was not the only option.

"If you think about the events of the last 24 hours and the way that the report's been received, it demonstrates to me that the council doesn't have the institutional capacity to do what's needed to be done," he said.

"I suppose one other option that could be considered - but it might be unpalatable in certain quarters - is quite simply for the mayor to resign."

The review found a leadership void, the election of a divisive councillor, and relationships between councillors among the problems the council faced.

"If the commissioners are sent in, then it would show councils that the minister and Internal Affairs aren't prepared to sit back and let things stick along as usual," Dr Asquith said.

"This has been the case for too long, and that council needs to pull their socks up. But the problem is that councils in a number of places don't have the wherewithal to make the changes that are needed, because they don't see that there is a problem.

"It's business as usual."

Three Southern mayors - Clutha's Bryan Cadogan, Central Otago's Tim Cadogan and Gary Kircher from Waitaki - signed a letter for the review, detailing their concerns about Sir Tim's ability to govern.

Both Cadogans declined to speak - saying they did not want to distort the process.

Kircher would not comment on the concerns raised, saying he wanted to preserve the reputation of Sir Tim after his many years of service to the community.

"It's about how the people of Invercargill can find the right solution for them and make sure that they have their democratic processes looked after, but ultimately there's a solution there which helps Sir Tim retain his good reputation and for local government to also retain its reputation. That's the ideal situation there."

Dr Asquith has never heard of mayors speaking out in a review like this before.

"It was widely known in local government circles in the middle of last year that perhaps Tim Shadbolt ought not to seek re-election, and it also raises the question as to the fact that if people realised things were degenerating so much in Invercargill, why it took so long for Internal Affairs to intervene."

He is calling for a fundamental review of local government in New Zealand, which could mean regular on-the-job training and development for elected members.

Former Dunedin City councillor and Southern District Health Board member Richard Thomson wrote the report, saying he found the council was facing a number of challenges.

"It is impossible to escape the general conclusion that this is a council in trouble because it does not appear to have a shared culture, is struggling to work together cohesively, has a number of councillors who are at odds with the CEO, and for whom there has been a significant impact from a couple of changes in personnel since the last election. But most of all, it is a council operating in a leadership void."

He was not confident the council could recover on its own.

"Whilst it is the ICC rather than myself who is being asked to provide reassurance that they could meet the Crown's expectations of a high-performing council, I do not believe in the absence of appropriate intervention that such an assurance could be confidently given."

Yesterday the council revealed its action plan - appoint two external appointees, develop a clear set of delegations for the deputy mayor, include training for elected members, and measure progress through annual evaluations.

Minister of Local Government Nanaia Mahuta said intervention or a Crown adviser was not on the agenda yet.

Minister of Local Government Nanaia Mahuta says support and advice is available to Invercargill City Council. Photo: RNZ / Richard Tindiller

"First and foremost we have to have confidence in councils to be able to make good decisions and then if that's not the case there are thresholds that need to be met for the government to make decisions about what level of support may need to be provided. But, you know, we've made ourselves available to be able to provide advice."

Yesterday Mayor Tim Shadbolt defended himself, saying the report was scapegoating him for the failings of the council - despite the report being unanimously accepted earlier this month.

The Department of Internal Affairs said his statement didn't change the fact the council had agreed to develop and implement an action plan.

Ministerial Advice Monitoring and Operations director Anita Balakrishnan said the implementation of that plan was the council's responsibility.

"We expect the roles and responsibilities of the observers will be outlined in the plan when it is ready. Once the plan is in place, the department will monitor the implementation of the plan," she said.

"The department was aware of the concerns of other councils when it wrote to Invercargill City Council in August 2020. We cannot comment on the actions we will take until we have seen the action plan. Once we have reviewed the action plan, we will provide advice to the minister about what actions she might take."