News of the meeting has been greeted with disappointment by Local Government New Zealand, the group which represents the country's 78 councils.
President Lawrence Yule - also Hastings' mayor - said: "I'd have to say I'm disappointed.
"I would have preferred the issue was raised with us and we could have organised a meeting."
Mr Yule said he had learned of the arrangements after a call from Ms Bennett's office saying she had been invited to attend. He had tried to get hold of the organiser, Hutt City Mayor Ray Wallace, to find out more but had been unable to speak to him.
Mr Wallace confirmed to the Weekend Herald he had organised the meeting, saying it was driven by concerns the Local Government Commission had made its mind up in areas currently under focus.
Four parts of New Zealand are facing Super City-style inquiries by the Local Government Commission - the Far North, Hawkes Bay, Wairarapa and Wellington.
"It has been like-minded mayors who have made it known they have concerns about the process," he said.
He believed the commission would recommend a Super City for Wellington - a solution he believed the public would not accept. "Why would we want to go through all that heartache if there is a better way?"
Also attending was Opotiki Mayor John Forbes, who is vice-president of Local Government NZ. He distanced his role in the organisation from the meeting, saying: "It's not an official Local Government NZ meeting. It's some mayors concerned about what is shaping up."
Taupo Mayor David Trewavas will also be at tomorrow's dinner and drinks.
Porirua Mayor Nick Leggett said the meeting smacked of exclusivity and secrecy. "It's very odd the vice-president of Local Government NZ would be leading a secret squirrel meeting of mayors trying to circumvent a judicial process under way in several areas of the country.
"Why they would need to have quiet little sneaky meetings at flash resorts when they should be talking to their communities is beyond me."
Hamilton Mayor Julie Hardaker - who was not invited - said the matter was one for Local Government NZ. "It's healthy to have this discussion but let's have it together."
Ms Bennett said she was not attending but "amalgamation of councils is not part of our agenda". She said it was ultimately up to communities to decide.
Commission chief executive Donald Riezebos rejected any suggestion of "pre-determined outcomes". He said the inquiries were being done in good faith and according to the law.
Breakaway mayors
• Ray Wallace (Hutt City)
• John Forbes (Opotiki)
• David Trewavas (Taupo)
• and nine others
