Alexander 'Greek' Thomson's celebrated Egyptian Halls is under "real threat of structural collapse", according to its owners.

Union Street Properties has posted a video on YouTube which states the building could collapse due to a number of "trigger events", including the failure of floors slabs, columns and beams.

However, Glasgow City Council disagrees with the video. A spokesman said a survey, carried out by the authority around 18 months ago, found "no danger of imminent collapse".

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Upper and ground floors in the property are owned by separate companies – Union Street Developments and Union Street Properties – both run by Derek Souter alongside his brother Duncan and Kelvin Kerr.

They recently commissioned structural engineers Will Rudd Davidson to examine the famous building.

The engineers' report states: "The building is now in an unsafe condition and structurally unpredictable which has primarily been caused by the deterioration of the roof and upper floors from continued water ingress over a prolonged period of time and the fundamental lack of robustness in the structure, with the potential for a trigger event to cause a structural failure which could have serious consequences, with the risk to public safety and damage to surrounding buildings."

"Key decisions" now need to be made, it adds. "While these decisions may be a difficult compromise for some parties, it is no longer possible to leave the building in its current condition."

Proposals for future redevelopment, which are being recosted, include facade retention or demolition, with a new build. Demolition would be "culturally unacceptable", the engineers say.

However, preservation is "all but impossible to achieve" as 85% of the structure would need to be replaced.

The video also claims any collapse could affect a substation in the basement which supplies electricity to nearby properties, including Central Station.

A Glasgow City Council spokesman said: "We do not agree with the content of the video and how it is being presented. We carried out a survey of the building around 18 months ago and found no danger of imminent collapse."

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They added the building's structural condition is the responsibility of the owner and they look forward to viewing proposals for future uses of the property.

The Union Street gem was recently shortlisted for heritage organisation Europa Nostra’s seven ‘Most Endangered’ programme, a campaign to raise awareness and push for action on at risk monuments.

The Alexander Thomson Society and the Society for the Protection of Ancient Buildings collaborated on the application. A petition, named Save Egyptian Halls, has also been launched on change.org, with over 3500 signatures so far.