Rotorua Museum could be closed for "quite some time" after initial reports show 70 per cent of the building was affected by last week's earthquake.
The Category One heritage building was closed without warning on Friday after new cracks were discovered in the historical part of the structure.
The cracks are believed to have been caused by the 7.8-magnitude earthquake that struck the South Island last Monday.
Museum director Stewart Brown said engineers looking into the damage had reported the museum was "not in very good shape".
"Engineers will be carrying out further investigations with a follow-up report expected on Friday. The museum will be closed until at least next Wednesday."
But Brown later conceded he was doubtful the museum would reopen next week.
"There is potential it could remain closed for quite some time."
Seventy per cent of the building had been affected by the quake and all objects in those areas, other than the marble statues, have been removed.
A detailed seismic assessment was in process when the earthquake hit. Before that, a less-detailed visual report was conducted in 2010.
Strengthening to the building was made in the 1980s and mid-2000s.
Brown said he was not prepared to release images of the damage, believing it would be misleading.
"The cracks measure millimetres and primarily in the foundations of the building, the pillars, beams, floors and walls."
Brown reiterated there was no danger of collapse and the closure was a precautionary measure.
The 45 museum staff have been put on special leave with pay.
"At this stage we have no idea what the cost will be to fix it. Being a Category One heritage building I find it hard to believe the community won't pull together to make it work."
Brown said he did not believe the closure would affect tourism in Rotorua and free guided tours were being provided of the Government Gardens, twice daily.
Rotorua Lakes Council chief executive Geoff Williams said the museum had three insurance covers.
"The insurance is for the building itself, loss of revenue and fine arts collection. There will be some cover from that but the extent is what insurers will want to look at."
- Damage to 70 per cent of the building
- Damage primarily to museum's foundations
- All items removed from damaged areas
- Follow-up engineer report due Friday
- Museum is likely to be closed for quite some time
From the council:
Will insurance cover this?
Rotorua Lakes Council has three types of insurance cover for the museum: for the building itself, loss of revenue and the fine arts collection.
Insurers have been notified about the process being worked through.
What about the art collection?
The museum's art collection contingency plan is already being actioned. All objects in the affected parts of the museum have been removed, apart from the collection of marble sculptures. Professional advice is being sought about moving these as they are very heavy.
Is the museum in danger of collapsing?
Previous assessments have deemed the building safe to occupy. There have been cracks in the historic part of the museum for many years and these have been monitored but the building is not in danger of collapsing.
The damage sustained last week is new damage and council has decided to remove the public risk by closing while the extent and nature of that damage and the level of risk it poses is assessed.