"Te Papa has the national collection and because it's in Wellington and one-third of the country's population is in Auckland, Aucklanders don't have access to that collection," he said.
"It can only fill a small proportion of what it actually holds - in fact, probably about 6 or 7 per cent. And that means a whole lot of the national collection is down there but is not seen."
The building would have a name such as Te Papa North, the working title of the project.
Mr Keith said the group had not focused on what the building itself would look like, but rather on how it would be used.
He emphasised that it would not look to replace the Auckland War Memorial Museum or the Art Gallery.
The group had already met the directors of those galleries as well as the Maritime Museum, who were enthusiastic about the proposed project, Mr Keith said.
"They can also use those exhibition spaces for major international exhibitions they can't accommodate."
He said the group proposed linking Te Papa North with local museums in several ways, including a bus service.
Auckland Council's 30-year draft plan has included a signature public building for the headland park in Wynyard Quarter, which could be 10 to 20 years away.
Waterfront Auckland chief executive John Dalzell said the earliest the bulk liquid industry would relocate from the headland was 2016, but more likely to be 2019.
Mr Dalzell said many people would want input into the park and signature building on Auckland's most valuable harbour site.
- additional reporting by Bernard Orsman
