More details have emerged about the asbestos contamination of collections at Motat, and what it will cost ratepayers to salvage what's worth keeping.

Auckland councillors have agreed to give the museum an extra $2.1 million in the next financial year, bringing its annual funding to $15.2 million.

Motat director Michael Frawley said the museum needed extra money because items at an off-site collection facility have been contaminated with asbestos, and it will need to recover the items that are worth keeping.

"We store approximately 80 per cent of our collection off-site. We have to move those items, clean up, and relocate them."

Frawley has told a council committee meeting the museum will need to employ extra staff to determine "whether it is worth retaining those items because they're historically significant or have some other importance to the museum, or whether they should be disposed of".

In the long-term, the museum is also seeking another $100 million from the council and $50 to $60 million from private sponsors to fund a much larger redevelopment.

In a statement, the museum said the contamination was unforeseen, and occurred in a building housing Motat's large collection of items like buses and cars.

"The museum is working closely with asbestos removal experts to resolve this issue and relocate the affected objects to new storage premises following their decontamination.

"Many New Zealand buildings of a certain age were built with material containing
asbestos and unfortunately this particular leased building has had some degradation.

"Once this became known, Motat brought specialist consultants on board to advise the museum and formulate a plan to address the problem.

"Additional resources will be allocated to the process of cleaning, decontaminating and moving large artefacts which has in turn expedited Motat's current collection review."

The museum has been under new management, after a report criticising the way it operated was leaked to the Weekend Herald in 2014.

The report, written in 2012, said under the previous management the museum was "dysfunctional", riven with "childish" infighting, had exhibits of doubtful quality, and spent ratepayer funding poorly.

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Frawley said since its relaunch, the museum had been trying to rebuild its reputation, to attract corporate partners and private sponsors who could support future development.

He said in addition to issues with its offsite collection, the museum also needed to make major improvements to its on-site buildings.

"The roof leaks in most of the buildings, most of the building contains asbestos in some shape or form. We don't know where the pipe work actually goes."

The revelations come as Auckland councillors have agreed to launch an independent review into the city's cultural institutions.

Mayor Phil Goff said funding agreements and legislation have prevented Auckland Council from having proper oversight of how Motat and other institutions spend council funding.

"We're investing a huge sum of money. To have a 21st century governance and accountability framework, I think, is absolutely essential.

"We certainly don't have the ability to set priorities, and ... a system that ensures transparency, accountability and value for money."

Motat said it strongly supported the review, which has been discussed for several years.

"This is a project which has been discussed by council for some time and is something which Motat supports and welcomes for this sector.

"Motat is pleased to hear that this review has now been formally adopted by a unanimous vote of council."

A council report shows the review will address "tensions" about the funding of Auckland Museum and Motat, and the need for long-term storage facilities for Auckland Libraries and other institutions.

It will also address the future of the Maritime Museum, whose waterfront lease expires in 2025, and Auckland Stardome, whose lease may expire in 2027.

Goff said Minister for Arts, Culture and Heritage Maggie Barry had indicated the Government would be open to changing the legislation that governs the institutions.