The Star's half-a-billion dollar plan to build a luxury hotel and residential tower on its Pyrmont casino site appears unlikely to proceed, after the state's planning department signalled it would not support the development.

Citing "unacceptable visual impacts due to its scale" and poor design, the NSW Department of Planning, Industry and Environment said the 66-storey building was not in the public interest.

Proposed tower for The Star. Credit:Star.com.au

The proposed tower would be "unduly prominent", have adverse impacts on views from residential properties and cause overshadowing in winter, the department's report to the state's independent planning authority said on Thursday.

"The [plan] would introduce a new tower form that is inconsistent with its immediate context and would result in unacceptable visual impacts due to its scale, isolation and visual dominance of the existing Pyrmont character and fails to promote good design and amenity of the built environment."