The council's staff who worked at the building were briefed about the discovery on Friday and the council has given itself three months to find alternative premises. The risk was only significant if the outside of the building was disturbed.
Green said the building needed to evacuated until the asbestos issue was fixed.
A report to council on Thursday outlines six options for addressing the council's long-term accommodation problem including undertaking necessary health and safety work, refurbishing either part or all of the existing building or the council's preferred option - building a new one.