Mr Williams said questions needed to be asked of the Hastings District Council about its decision to increase its budget behind closed doors. "We've had councillors contact us concerned about the secrecy of this funding," he said.
In the middle of last year Hastings councillors voted to include the $35,000 amalgamation campaign marketing spend in the council's annual plan.
Hastings Mayor Lawrence Yule yesterday said councillors agreed to increase the budget to $50,000 at a closed-door workshop in December.
Hawke's Bay residents are likely to vote in a binding poll on the amalgamation issue about August. Mr Yule said it was unlikely council would commit more money to the issue ahead of the poll.
"We put our message out to our ratepayers as to why we thought what we were doing was the right thing and to support our argument. We're certainly not interested in tit-for-tat spending of ratepayers' money."
Napier Mayor Bill Dalton said he was "uncomfortable" spending money on an amalgamation campaign, but Napier, Wairoa and CHB were left with "nowhere to go but to put the other side of the argument" after Hastings' decision to spend money on a campaign. Mr Dalton said while councillors had voted in favour of spending about $15,000 on the pamphlet drop, he could not recall whether the decision was made at a public meeting or behind closed doors.
Central Hawke's Bay Mayor Peter Butler said his council had contributed $3800 to the pamphlet drop campaign and made the decision at a public-excluded meeting because it did not want details of the campaign to emerge before it was launched.
Wairoa Mayor Craig Little said his council also contributed an amount in the low thousands of dollars as the costs were shared among the three councils on a population basis.
"We just can't compete against the big boys," Mr Little said.
Like Mr Yule, the three anti-amalgamation mayors said it was unlikely their councils would spend anything further on the campaign to convince the public to oppose amalgamation.
Legally local authorities cannot campaign on the amalgamation issue once the Local Government Commission has released a "final proposal" in their region.
In the case of Hawke's Bay, a final proposal could be released by next month.
Meanwhile, opponents have been quick to parody a privately funded pro-amalgamation billboard campaign involving hoardings supporting the council merger proposal spring up around the region during the past week.
A Better Hawke's Bay, the group that sparked the Local Government Commission's amalgamation proposal and is running the "Amalgamate Hawke's Bay" marketing campaign, said its signage with pro-amalgamation messaging was being put up "from Waipukurau to Wairoa".
The billboard blitz comes in the same week that three councils opposed to amalgamation - Napier City, Wairoa District and Central Hawke's Bay District - completed a letterbox drop of an anti-amalgamation booklet to homes across the region.
The battle to win the favour of the districts' voters - who will have their say in a binding poll later this year - has also gone online, with a doctored photo of a Waipukurau ABHB billboard doing the rounds.
The photo adds a Tui "Yeah Right" treatment to the lobby group's "Amalgamate!" message.
"It looks good, we're sending it all around Hawke's Bay," Mr Butler said yesterday.