The Mackintosh Building is to be partially demolished.

Glasgow City Council announced the decision today that the building is in danger of sudden collapse and action must be taken.

The south facade of the building, which backs on to the O2 ABC, will be reduced and the east and west gables of the building may also be taken down.

The council said a "partial dismantling" will begin in the coming days but the famous front of the building on Renfrew street could yet survive.

The council said recent remote surveys and close-in surveys from baskets suspended from cranes have revealed more substantial movement in the walls of the building than previously thought.

This means a sudden collapse of parts of the building is likely, rather than possible.

Glasgow City Council’s Head of Building Control Raymond Barlow said: “This building has undergone substantial stress in recent days. With each passing day a sudden collapse becomes more likely.

"It has become urgent that we take down the south façade. As the process begins it will be likely that the other walls will also need to be reduced.

“We do not know what effect this will have on the rest of the building so I have to be clear this site remains dangerous and is becoming more dangerous. It is particularly important that people observe the cordon which remains in place.”

Fire broke out at the world-famous School of Art centrepiece two weeks ago, the second devastating blaze in four years.

More than 100 firefighters battled to save the building but the fire was more widespread than before when they arrived and spread throughout the building, also engulfing the O2 ABC music venue on Sauchiehall Street.

In the following days building control experts inspected the building to determine whether it could be saved.

Initial possibilities included another restoration project, estimated at around £100million or taking the remaining structure down and rebuilding it brick by brick on the current site, which could cost as much as £200m according to construction experts.

Nicola Sturgeon said after visiting the site, the Scottish Government was ready to do “anything we reasonably can” to ensure the Mackintosh Building has a future.

A spokeswoman for the Glasgow School of Art said: "The detailed visual assessment shows that damage to the Mackintosh Building is significantly greater than had initially been anticipated from ground visual assessment and the data from the drone and scanning footage which were undertaken last week.

"The Glasgow School of Art’s site contractor Reigart, together with its structural engineers, David Narro Associates, are using all this information to develop a plan of works to achieve structural stability of the building. This will be agreed with Historic Environment Scotland (HES) and Glasgow City Council (GCC) Building Control. All parties are working in close collaboration to allow plans to be developed and agreed as quickly as possible.

"The areas of significant concern are the east elevation, the west elevation and sections of the south elevation. The plan of works will involve Reigart undertaking extensive down takings and potential structural bracing. 

"Due to the condition of the Mackintosh Building this work will be undertaken in a highly controlled way to minimise any potential risk of failure and be sufficient to achieve structural stability of the Mackintosh Building.  

"The aim of the GSA and GCC will be to return normal access for residents and businesses as soon as possible. 

"When the plan of works has been agreed with HES and GCC Building Control, we'll let people know."