Refurbishment work at the Telstra Building on Kent Street, Deakin, came to a halt on Friday, with WorkSafe ACT and the Environment and Sustainable Development Directorate issuing stop-work notices to the contractor for breaches in licensing and building approvals after asbestos was found on the site.

Construction union officials inspected the site on Thursday and raised various concerns with authorities.

The contractor, Business 2 Business Commercial Fitouts, a Sydney-based company, voluntarily shut the site after the inspection.

Dean Hall, ACT branch secretary of the CFMEU, said the building's asbestos register was not accurate, but the correct process of a subsequent asbestos audit and development of a management plan was not followed by the contractor.

A Telstra spokesman said it was ''aware that a contractor working on behalf of Telstra found some asbestos at a vacant part of the Telstra site''.

''The contractor took immediate action to ensure the safety of their employees … [and] is now working with appropriate authorities to ensure the site remains safe for anyone who works there.''

A spokesman for the ESDD said the stop-work notice was issued under the Building Act ''due to there being no building approval in place for the work being undertaken''.

''The head contractor did not have the appropriate licence, the asbestos removalist is licensed in the ACT. However, there were no approvals in place to undertake the work. None of the work on the site had the relevant approvals.''

It is unknown how long the site will be closed, with a number of approvals required.