America's Cup heavyweight Brad Butterworth says Team New Zealand have been "caught out" as the defender and challenger traded blows over the regatta courses.
Team NZ on Thursday suffered a knock back when an America's Cup arbitration panel ruled out two of the five courses for the event off Devonport's North Head.
It has thrown the whole concept of the publicly backed 36th America's Cup into doubt, with TNZ claiming that the city views will be lost for the world audience, and the public will miss out on the best viewing experience.
TNZ fired up the war of words when it tweeted an attack on Luna Rossa on its official social media account, claiming the Italians were "destroying" the public's ability to view the regatta early next year
TNZ claimed it was "outraged that after three years of planning a land-based stadium event" the Italian challengers had wrecked the concept. It accused Luna Rossa of conducting a "campaign through the arbitration panel".
But Butterworth, who was hired by Luna Rossa last month, told NZME that the British and American teams backed the Italian position.
The typically confused and bitter America's Cup spat centres on using the B and C courses. Butterworth says the challengers discovered they would not have access to those areas during the challengers' Prada Cup, handing a tactical advantage to the home team defenders.
This was in contravention of the AC rules which say it should be a 50/50 situation. If negotiation fails to resolve the situation, courses B and C – which offer prime public viewing - will be excluded for the challenger series and America's Cup itself.
"It's pretty obvious to everybody who is wrong here," Butterworth said.
"It's a bit of bad behaviour and they've been caught out by the arbitration committee…everybody from challengers side has thrown their hands up in horror…there have been submissions written by all the teams in support of this action."
Kiwi yachting legend Butterworth - a four-time America's Cup winner - is still hoping that negotiation can bring the two courses back into play.
But he said communication with TNZ was difficult.
"It's very hard to get to the top echelon and to talk them on any given day," he said.
"We've got a representative from the Luna Rossa team, they don't even talk to them about the running of the event.
"The relationship's not great, that's obvious to everybody. But let's try and fix that and come up with a solution because it is a yacht race at the end of the day."
TNZ boss Grant Dalton declined to be interviewed by NZME, but his statement read: "Quite frankly we are outraged by this decision, it has gone against everything we have been trying to achieve over the last three years with no consideration to the effect this has on the public of New Zealand and the city of Auckland."
TNZ's statement said that "images with Auckland city as a backdrop during racing have always been a critical part of showcasing Auckland and New Zealand to the world in an event with a significant global audience, and another reason for the original race course design".
Whereas Butterworth said course B and C had been removed "unbeknownst" to the challengers, Dalton firmly rejected that in a statement to NZME.
"To suggest that this was an arrangement between the defender and the local authorities is simply mischief making and factually incorrect."
Dalton said it was safe to "assume" that a contractor employed by TNZ and Luna Rossa had informed the Italians of the change early this year.
Meanwhile, Auckland mayor Phil Goff has asked the syndicates to find a solution.
"We want the America's Cup to be as accessible to as many Aucklanders and New Zealanders as possible. I would encourage all parties to work together to find a better solution," Goff said in a statement.