Authorities in Christchurch have announced at least 184 buildings in the Christchurch CBD will require major work following the February 22 earthquake - including demolition.

Warwick Isaacs, director of planning and transition, said to date 128 buildings have been identified as in line for demolition, 37 for partial demolition, and 12 are required to be made safe.

Of those, seven have been identified as "critical": the Rolleston Court apartments, New Zealand College of Early Childhood Education, Community House, BDO Spicers Christchurch, the Hotel Grand Chancellor, Harcourts Grenadier, and Kenton Chambers.

Mr Isaacs said those buildings identified as critical were generally five storeys or higher, were close to important infrastructure and thoroughfares and posed a risk to nearby buildings.

At this stage no decisions had been made about the method and timeframe of demolition of those buildings marked as critical.

However, Mr Isaacs said the demolition of some of the smaller critical buildings was "imminent".

Of the buildings identified as needing to be demolished, work had began on around 100, Mr Isaacs said.

Civil Defence national controller John Hamilton said the Town Hall was not on any demolition lists.

Before buildings are demolished, insurers and owners are consulted before the authorities sign off on the demolition order. Heritage officials are also consulted in the process, Mr Hamilton said.

Christchurch Mayor Bob Parker said there were questions around whether damaged buildings in the city could have a future.

"Do these buildings still have an economic use?

"You can speak to anyone in those buildings [at the time of the quake] they will say 'I am not going into that building'," he said.

"The perception of safety is is going to be different to the reality of safety."

"The fact of the matter is we are looking at a different city.