A 7-metre long interactive touch wall to be installed at Christchurch's new central library will cost $1.24 million, it has finally been revealed.

The figure comes after the Ombudsman called on the Attorney-General to launch enforcement proceedings against the city council for not releasing the information.

The Taxpayers' Union originally requested the cost of the touch wall, but was denied by the city council.

It then complained to the Ombudsman.

Last month the city council got a slap on the wrist from the Ombudsman for not releasing the cost, and was told to reconsider within 21 days.

The wall was provided by Wellington-based Gibson Group, which did not want the cost revealed because it could "prejudice its commercial position".

The city council has finally released the $1.2 million cost.

Head of libraries and information Carolyn Robertson said having the largest interactive touch-wall in the country was a significant coup for Christchurch.

"The scale and complexity of this technology is unlike anything else currently available in New Zealand, and to have it located inside our new central library is a major win for the city – it will be a big drawcard for residents and visitors alike.

"With regard to the $1.24 million cost, it was always the Council's intention to release the figure – it was simply a question of timing."

Chief Ombudsman Peter Boshier​ said he was disappointed the city council had not released the cost within the timeframe required under the law.

"My role as a watchdog for Parliament is to make sure official information law is not undermined by agencies ignoring their public duty when it arises. I take any breach of public duty extremely seriously. I do not have enforcement powers myself so I am referring the case to the Solicitor-General," he said.

The wall will allow users to swipe their way through a virtual world of information will be installed between the library's ground-floor entrances.

The $1.2 million touch wall cost is on top of the $4.17 million cost of Turanga's IT and audio-visual fit out, which will include laser cutters, 3D printers, virtual reality consoles and robotics.

- Star.kiwi