Plans to expand the Sydney Opera House's function centre will have significant and unacceptable impacts, the City of Sydney council has warned.
Moreover, the changes are a clear violation of the vision of its renowned designer, the late Jorn Utzon.
The plans, which are part of the Opera House's renewal program, include adding a new function centre to replace the events marquee on the northern boardwalk.
But in a submission objecting to the proposal, the council said the technical work involved would cause irreversible changes and prevent any future plans to restore the Habourside restaurant.
"This is a loss to the community and to the significance of the place," council's director of city planning Graham Jahn said.
"It is in direct contradiction with Jorn Utzon's vision for the Opera House."
Converting the ballet rehearsal room into a function centre kitchen would impact on the iconic building's heritage status.
Ballet dancers would also be forced to cross the central passage to access the relocated rehearsal room, a plan "incompatible" with the Opera House's status as a world-class performing arts centre, Mr Jahn added.
'Worse, it prioritises the function centre use over of the performing arts," he said.
The council concluded it was opposed to the function centre changes and was unable to provide recommended conditions of consent.
A spokeswoman for the Opera House said the upgrade complied with the Utzon Design Principles and had been overwhelmingly backed by heritage and architectural experts as well as the broader community.
The changes had the support of the Opera House's independent architect panel and conservation council, along with Opera Australia and The Australian Ballet, she told AAP in a statement.
"The Opera House considers it has addressed several of the City (of Sydney's) key concerns," she said on Wednesday.
