Security has been stepped up at the soon-to-be demolished Harris Academy following a fire at the Perth Road building.
The move by contractors Robertson Construction also comes after an attempted theft of copper from the site.
West End ward councillor Fraser Macpherson says he has received confirmation that extra security is now in place overnight and at weekends.
Mr Macpherson added: “I am pleased that the contractor has increased security so that there is round-the-clock security when the construction staff are not present.
“I am grateful for the prompt and positive response to my request given the recent fire incident and an attempted theft of copper.”
Dundee East station manager Bruce Farquharson said: “It was a suspicious fire, likely to have been set by children playing in the building.
“This is the first fire at the derelict former school site we have been called to. I hope it does not become a pattern or recurring incident.
“The former Harris Academy is a demolition site. It is a very dangerous place to be and people can get hurt there very easily.
“But also, fire-setting is a very dangerous thing to be doing, not just for the people setting the fires but also the fire service when we deal with it and other communities in Dundee.”