Scottish artists are demanding that Glasgow School of Art end its contract with a major building firm which was involved in a blacklisting scandal.

Kier Construction was appointed this week as the main contractor for the restoration of the Mackintosh Building at the Glasgow School of Art (GSA).

Earlier this year Kier, along with a number of other leading construction firms, apologised in the High Court to hundreds of workers which were blacklisted via a vetting firm called The Consulting Association, which was closed in 2009.

Almost 800 workers, blacklisted via files held by The Consulting Association, won an estimated £75m in a wave of compensation settlements.

It was alleged by unions that workers were denied work on construction sites after being included on the files for raising health and safety issues, trade union activity, and political views.

The existence of the blacklist was uncovered by the Information Commissioner’s Office when it raided the offices of the Consulting Association eight years ago.

Last night Kier said it does not condone blacklisting in any form, and operates in a responsible and ethical manner, and noted it had apologised and paid compensation to those affected.

This week the GSA announced that Kier had won the contract to to oversee the restoration of the fire-damaged Mackintosh Building.

The Scottish Artists Union, currently representing more than 1400 professional artists living and working in Scotland, has written a letter to the art school urging it to "review its decision, and to reconsider this contract."

It says that the union is "deeply concerned and disheartened by the decision of Glasgow School of Art’s Board of Governors to award the contract for the renovation of the Mackintosh Building to Kier Construction, a company that admitted to the blacklisting of workers engaged in trade union activity.

"The ‘Mac’ building was renowned throughout the world for its craftsmanship; innovative use of materials; its functionality and its commitment to the values of the arts and crafts movement.

"It's therefore incongruous that the GSA have awarded £25 million of Government funds for its restoration to a company that has engaged in blacklisting activities."

It adds: "The Scottish Artists' Union expresses our continued support to workers and their families affected by blacklisting. We oppose this decision to award Kier Construction this contract and also question the procurement methods that led to this decision.

"The destruction caused to the Mac devastated our community and many across the world, particularly the hundreds of students preparing for their degree show. Had it not been for the professional, skilled response of unionised firefighters in the FBU [Fire Brigades Union], the damage would have been much greater.

"The Glasgow School of Art is a world leading institution, known as innovative and progressive.

"This contract undermines the distinct values of the institution."

A Kier spokesperson said: “In 2009, the Information Commissioner's Office (the ICO) investigated and closed a database known as The Consulting Association (TCA).

"Kier co-operated fully with the requirements of the ICO and of the 40 companies that used TCA, Kier was one of eight who have proactively apologised and paid compensation to those affected."

He added: "Blacklisting is contrary to Kier’s policy of conducting its business in a responsible and ethical manner.

"Kier does not condone blacklisting in any form."

Earlier this week Liz Davidson, Mackintosh Restoration project manager said: "Kier provided the GSA with a tight, extremely well structured, highly competent and confident bid – combined with a competitive tender price. The team they have assembled has a depth of experience and knowledge combined with solid construction methodology and practice."

A spokesman for the Glasgow School of Art said: "At every stage of the restoration of The Mackintosh Building The Glasgow School of Art has operated in line with the Scottish Government an EU procurement legislation both in the PQQ [Pre-Qualification Questionnaire] and formal tender process."

At the time of the court case, Len McCluskey, general secretary of the Unite union, said: "The massive scale of the agreed damages shows the gravity of the misdeeds of major construction companies which created and used the Consulting Group as a vehicle to enable them to blacklist trade unionists."