Building control officers in Glasgow have warned people to stay away from the site of the art school fire.
They revealed concerns about the end walls of the building, which could fall into the street "without warning".
The Glasgow City Council officials urged everyone to observe the exclusion zone surrounding the Glasgow School of Art and neighbouring buildings on Sauchiehall Street.
There have been reports of people breaching the cordon.
Some of the restrictions on movement in the area are to be eased.
Traders on Sauchiehall Street had warned that the fire could spell the end for some businesses in the area.
Residents living within the exclusion zone had been unable to return home since the fire engulfed the iconic Mackintosh Building on Friday night.
Glasgow's head of building control Raymond Barlow said: "I fully understand people's desire to get back into their property and if we could safely do anything to facilitate that then we would.
"However surveys in recent days have shown us that the West and East elevations remain of significant concern
"This means that there is a risk that parts of the building might fall into Scott Street or Dalhousie Street. This could happen without warning."
Mr Barlow said he and his colleagues are working on a plan which will allow them to make a proper survey of the structure.
"Working with The Glasgow School of Art and Historic Environment Scotland we are currently devising a methodology to allow us to examine the building up close," he said. "However it will be at least the early part of next week before we are able to do that."