The fire is thought to have destroyed restoration works being carried out by Kier

Experts are predicting the entire Glasgow School of Art will have to be rebuilt after fire gutted the grade A building on Friday night.

Kier was working on a £25m restoration project following a blaze which struck the school’s library back in May 2014.

The contractor was appointed in June 2016 and was scheduled to be completed by the end of this year. Pictures over the weekend show that this has been destroyed as well.

The two-stage project had involved restorating the Mackintosh building’s roof before restoring the west wing and upgrading the east wing interior of the school.

The latest blaze broke out of Friday night and took 120 firefighters to get under control.

The Scottish Fire and Rescue Service’s deputy assistant chief officer Peter Heath told the BBC the fire damage was “exceptionally significant” and that it was likely that the work carried out to repair the damage from the last fire had been destroyed.

Depending on the assessment of the present building’s facade, repair work could £100m with some reports suggesting the entire building may have to be pulled down.

A Kier spokesperson said: “An agreed fire safety strategy was implemented for the build phase of the Mackintosh restoration project, which combined measures for the protection of all those entering the site to work and to alert the authorities in the event of an outbreak of fire. 

“These included a smoke and heat detection system and regular evacuation tests as well as 24 hour, 7 days a week security and fire warden patrols by a team of three guards, originally appointed by the client after the 2014 fire and subsequently by Kier.   

“We continue to work with and support Scottish Fire and Rescue Service and our client as they determine the next steps for the Mackintosh building and site.  We have a passionate team of local construction and crafts people, skilled conservators, supply chain and engineering specialists who have worked incredibly hard on this iconic landmark, and together we are all keen to do whatever we can to help moving forward.” 

Kier beat out a shortlist of Balfour Beatty, Bam, John Graham and Sir Robert McAlpine to carry out the restoration works designed by Scottish architect Page\Park.