Miranda police are treating a fire at the former Caringbah High School site last Saturday as suspicious.
Police have no suspects but witnesses say they saw teenagers in the area shortly before the blaze.
Police also say they have approached Sutherland Shire Council about a demolition order for the site which they say is derelict and unsafe.
The fire was in the southern section of the high school which was abandoned several years ago when the school was consolidated at the northern end of the site. There was another fire at the site in April 2013.
A Sutherland Shire Council spokeswoman said they had a meeting with police and the site owner about the current condition of the buildings.
‘‘Council has spoken to the owner about the need to make safe any loose, burned material from the area, provide structural certification of the southern building, engage 24/7 on-site security and erect warning signs,’’ she said.
‘‘We have also spoken to them about securing all buildings and removing any associated fire damaged asbestos materials and engage a suitably qualified person to undertake an inspection of the property to provide an asbestos clearance certificate to council.’’
She said the council would work with the owner to ensure the site was made safe.
