The mayor of Invercargill is calling foul, saying his deputy stymied his travel plans and he will have to get a taxi from Wellington to Palmerston North as a result.

Sir Tim Shadbolt said in statement that he would have no choice but to take a taxi from Wellington to Palmerston North for the annual Local Government New Zealand conference on Wednesday. The distance between the two cities is 190km.

Deputy Mayor Nobby Clark initially approved expenditure on a rental car to travel between the two cities, but changed his mind in an email sent on Saturday, Shadbolt said.

He labelled the move "petty and small-minded" and accused Clark, who is running for the mayoralty, of having a conflict of interest.

However, Clark denied stymieing Shadbolt's travel plans, saying he did not suggest that the mayor should get a taxi between the cities.

Clark said it was a curious position he found himself in as a deputy, as he had to take on some of the duties of the mayor.

There were two issues at stake, firstly that Shadbolt wanted to add days away and secondly to use a rental car, Clark said.

He had no issue with adding extra days to the travel arrangements as long as additional costs were not borne by the council.

He believed the rental car would be for Shadbolt's partner and son to get around, Clark said.

In his statement, Shadbolt denied having his partner attend the conference would increase costs.

Clark said when the issue of a rental car came up last year in relation to the same conference, which was held in Blenheim, the council booked Shadbolt a rental car and recovered the cost in instalments.

His decision was about being consistent, Clark said.

The city had put rates up 6.53 per cent, which Clark voted against.

"It was a huge public debate about how people were struggling and I just thought, how can I in good faith take that stand then be a bit loose or flexible with costs related to the mayor going away?"

Shadbolt could apply to the council for reimbursement for rental car costs when the council sat again in the weeks to come, Clark said.

Councillor Peter Kett said he had been a longtime friend of Shadbolt.

The decision to deny the mayor a rental car was "disgusting", Kett said.

Shadbolt deserved a car, and while he could not drive due to health issues, his partner could, Kett said.