In July, the Dunedin Public Art Gallery and Christchurch Art Gallery made a successful joint bid for The Haymaker Series I-V, by Palmerston North artist Shane Cotton.
The galleries are the first owners of the 2m-high, 9m-wide acrylic-on-linen artworks.
The work consists of five large painted panels, hung side-by-side.
A Cotton artwork, about a third of the size, Lying in the Black Land, sold for $256,640 in 2010.
An Official Information Act request to the council on the price paid for the artwork was declined.
Council civic and legal manager Kristy Rusher said the artwork was covered by the council's fine arts insurance policy.
"Our insurer has requested us not to disclose the purchase price, due to their concerns that the piece would become a target for thieves if the purchase price is published.''
The insurer was unwilling to make an exception, she said.
The council needed to balance its duty to protect its assets with its obligation to explain how public funds were spent.
"In this case we are prioritising the protection of our assets on the advice of our insurer.''
The Christchurch City Council also declined an OIA request on its share, saying it was unable to release the information because it could harm Cotton's commercial position, and the council's ability to carry out commercial activities.
Arts commentator Peter Entwisle said an insurance clause blocking transparency for ratepayers was "stupid''.
The price of council-owned artwork should be publicly available.
"It's public money, it's been paid for by the citizens of Dunedin, it's their property and they have a right to know what they paid for it.''
DPAG director Cam McCracken said revealing the price would compromise the safety of the artwork and the insurance clause was designed to mitigate the risk.
To buy the work a "substantial'' amount of money was given by the DPAG Society.
The society supports the gallery by raising money, including through bequests, to buy art.
Mr McCracken would not disclose the percentages of the purchase price paid by the society and by ratepayers.
The work was the most expensive work the gallery had bought since he became director about three years ago.
He was unsure if it was the most expensive purchase in the gallery's history.
The artwork was stored in Dunedin and it would be displayed this year, he said. Cotton could not be contacted for comment.
● Another OIA request to the Dunedin City Council on art costs was declined.
The request asked how much the council paid University of Otago 2015 Robert Burns Fellow poet Louise Wallace to write the poem pine & sand for the launch of Dunedin's Art & Culture Strategy Ara Toi Otepoti - Our Creative Future on October 27 last year.
"The sum forms part of the poet's remuneration and is therefore personal information,'' the council said.
"We have undertaken an evaluation under the Privacy Act of the commission paid to the artist and have formed the view that privacy interests outweigh the public interest in releasing this information. Therefore your request is declined as it is withheld on privacy grounds.''
