An investigation is under way after asbestos was found at an Aberdeen school.
Aberdeen City Council said a potentially harmful material was disturbed during work at Bridge of Don Academy on July 12 and it has since been identified as asbestos.
The Health and Safety Executive (HSE) is being notified, a spokesman said.
The material was reportedly found behind a panel in a corridor at the school.
The Unite union has expressed concern about the risk of contamination.
Regional officer Tommy Campbell said: "There is great concern that the workers could be contaminated with a potentially dangerous substance, and if the full health and safety procedures relating to suspected asbestos exposure were not followed by management then these workers have left the site and run the risk of contaminating other workers and members of the public.
"Unite representatives have repeatedly made our health and safety concerns known about previous potential asbestos exposure incidents.
"It beggars belief that we have yet another serious, potentially dangerous situation where the management have failed to respond properly in line with health and safety regulations, and their own policies and procedures."
An Aberdeen City Council spokesman said: "On Thursday July 12 a potentially harmful material was disturbed within a corridor at Bridge of Don Academy where work to improve security is being carried out during the school holidays.
"The area involved was made safe and sealed off and the material removed for examination. The material has now been confirmed as asbestos.