Tests confirmed yesterday that five of six samples taken from the site on Friday were asbestos dust.

The asbestos was discovered during construction work on the roof of the building, and verified after calls from the Construction, Forestry, Energy and Mining Union.

Union representatives had arrived at the site after hearing reports that workers on the warehouse's roof were removing asbestos without full protective gear, while customers and staff were nearby. The company contracted to remove asbestos from the site, Australasian Technical Services, denied on Friday that any workers had worked without protective clothing.

The Office of Regulatory Services issued a prohibition notice on Friday, which would stay in place while the area is cleared, its acting executive director, Danielle Krajina, said. ''The site will remain closed until appropriate clean-up actions are completed and a decision will be made regarding lifting the prohibition notice, but this will depend on sufficient remedial action being taken,'' she said.