Asbestos confirmed in Opera House works

Electricians working on a $200 million renovation at the Sydney Opera House have been told by a union to stop work after tests confirmed the presence of asbestos fibres.

The Electrical Trades Union on Tuesday said it was concerned it took "several days" for the union to be informed and was demanding a full risk assessment along with immediate training for workers.

The ban covers any work that involves accessing risers and penetrations that carry electrical services between floors and through walls.

Builder Laing O'Rourke said the renewal works included a plan for the management of asbestos.

"Work is continuing on site as normal," a spokeswoman said in a statement.

"The existence of asbestos in original structures of the Opera House was always planned for as part of these major works, and we are taking every precaution and safeguard."

Asbestos awareness training had also been provided to employees and subcontractors since the work started, she said.

The area of concern was isolated and the material was removed safely last week.

Opposition arts spokesman Walt Secord echoed calls for a full risk assessment.

"A single asbestos fibre can cause deadly cancer," he said in a statement.

"No worker or member of the public should be exposed to deadly asbestos and work should not commence until it is 100 per cent safe to do so."