The Waitemata Local Board has been gagged from talking publicly about a secret deal condemning eight 20th century industrial buildings in the Wynyard Quarter to rubble.

The former Auckland City Council is understood to have done a deal with a private landowner, Viaduct Harbour Holdings, to leave eight buildings out of a list of 17 buildings deemed worthy of protection by Salmond Reed heritage architects.

The deal is so secret the Auckland Council will not even confirm its existence and last night members of the Waitemata Board were brought under the blanket of confidentiality to stop Aucklanders learning anything.

That did not stop the local board from passing a resolution supporting the Art Deco Society - the only body left fighting to save the buildings in the Environment Court. The board was told by the Auckland Council it could not join the legal battle.

Waitemata and Gulf councillor and former Auckland Regional Council chairman Mike Lee told the board that legal advice provided to the Auckland Council on the question of confidentiality was "cynical in the extreme and profoundly against the best interests of the Auckland Council, Waitemata Local Board and the people of Auckland".

The former Auckland Regional Council appealed against the Wynyard Quarter plan change, arguing that all of the 17 buildings should be scheduled. However, on legal advice, the Auckland Council decided behind closed doors in December to ditch the position of the Auckland Regional Council in favour of the position of the Auckland City Council.

Waitakere councillor Sandra Coney - another former Auckland Regional councillor - said the future success of the Wynyard quarter depended on the protection and retention of the marine and industrial heritage, otherwise it would just become another glass development.

Waitemata board chairman Shale Chambers said it was physical relics "that makes us as Aucklanders" and high quality design at the Wynyard Quarter development had to be in sympathy with the environmental and cultural heritage.

In a letter to the board, Historic Places Trust northern general manager Sherry Reynolds said it was necessary and desirable for the existing character of Wynyard Quarter to be kept, at least in part.

"Auckland's history is full of examples when the heritage and/or character of an area has been completely removed by the desire to build anew ... such as what happened to areas of the western side of lower Queen St during the 1980s," she said.

Ms Reynolds said the buildings may not appear particularly pretty or have a spectacularly significant history, "but what they provide is a clear visual link to how the Wynyard Quarter has been used historically".