National Theatre artistic director Nicholas Hytner has submitted a 3,600 word objection to the Southbank Centre's planned £120 million expansion.
As reported by Building Design, Hytner has contested that the proposed work (pictured above), designed by British architecture firm Feilden Clegg Bradley, will lead to "segmentation" of the South Bank area.
"The National Theatre is a close and supportive neighbour to the Southbank Centre but over the last few months we have noted with growing concern the scale of the Festival Wing proposals," he wrote.
"Having now read the full application and reviewed the details with our Board we regret that we must make a formal objection to the applications submitted on behalf of the Southbank Centre for planning permission."
Hytner, who is stepping down from the National in 2015, is himself overseeing an £80million redevelopment of the National Theatre, designed by Haworth Tompkins under the banner NT Future. But he says the Southbank Centre's own plans would have a negative impact on its neighbour.
He added: "We fear that the Liner building [a proposed new education space next to Waterloo Bridge] will be both a component of, and over arching metaphor for the further segmentation of the most dynamic arts complex in the country, if not the world.
"The view from the Olivier terrace, while not part of any recognised framework, is of considerable importance to the National Theatre, and is an important element of the NT Future project... All of this will disappear behind the Liner Building."
Hytner also cites in his objection the loss of sunlight to the National Theatre Square, currently home to the temporary NT Shed building.
The National Theatre's own building plans, which include the refurbishment and expansion of the Cottesloe theatre and the construction of a new cafe and glass-fronted production building, came under fire in 2010 when objections were raised by architectural historian William Curtis.
However, the plans were approved by Lambeth Council and the new Cottesloe (renamed the Dorfman) will open next year.
The Southbank Centre's £120million project, which will see a large glazed extension added to the Queen Elizabeth Hall, Purcell Room and Hayward Gallery complex, is currently under consideration.
Read the full text of Nicholas Hytner's objection to Lambeth Council in this thread
This story has been updated since its initial publication