Pouring taxpayer funds into the Art Gallery of NSW's proposed $450 million new wing would be a "direct insult" and an "absolute stake through the heart" of western Sydney.

The chairman of the Western Sydney Leadership Dialogue, Christopher Brown, said it would be considered an insult to the people of western Sydney if the NSW government spent more money on the art gallery at the expense of upgrading western Sydney's cultural facilities such as Campbelltown Arts Centre.

"Extending the Art Gallery at The Domain would be a direct insult to the two-and-a-half million people of western Sydney who have been denied government arts funding for so long," Mr Brown said.

"It would be an absolute stake through the heart of western Sydney to put more money into the art gallery — an institution that has resisted any move west for so long."

Mr Brown's warning comes as the NSW government considers a $30 million proposal to redevelop the Campbelltown Arts Centre.

The proposal includes a new 318-seat theatre, artist studios and rehearsal spaces, and renovating the front entrance.

"The proposed redevelopment will allow us to grow and keep up with the demand of a rapidly increasing population, 430,000 over the next 20 years", said the centre's  director Michael Dagostino.

"The NSW state government is building roads, hospitals and schools in the region because of this growth and arts and culture facilities should be considered as a part of this building program."

Mr Dagostino​ said he is yet to receive feedback on the proposed redevelopment: "We do hope that the process around the distribution of the funding, once confirmed, is fair and considers all submissions."

The  arts centre upgrade is one of a number of infrastructure proposals to cultural facilities in western Sydney identified in the Building Western Sydney's Cultural Arts Economy report released last year.

"South-west Sydney is turbo-charged but people don't only need paving and paths, they need cultural sustenance just like everybody around Sydney does," Mr Brown said.

Brown labelled the situation in which 95 per cent of the arts budget is spent in the City of Sydney council area as "truly bizarre".

"There's no other government department anywhere that comes close to that level of concentration," he said. "If we want to stop a revolt from the people of western and south-western Sydney, governments need to start supporting a decentralisation of the arts."

A University of Western Sydney board member, Mr Brown said he was "very confident" that NSW premier Mike Baird, who is also minister for western Sydney, understood that people in suburban Sydney should not have to travel up to 70 kilometres to listen to an orchestra, see an opera or enjoy great paintings.

"Western Sydney demands an investment of its own taxpayer-generated money in its own cultural facilities," he said.

The NSW government has set aside $600 million in its Cultural Infrastructure plan but has already committed to renovating the Sydney Opera House ($202 million) and redeveloping Walsh Bay ($139 million) in Sydney's CBD.

A spokesman for deputy premier and Arts Minister Troy Grant said the government is committed to growing the cultural sector in western Sydney, highlighting the relocation of the Powerhouse Museum to Parramatta.

"The government will consider infrastructure proposals from across Western Sydney including Campbelltown, Liverpool and Penrith with final funding decisions yet to be made," he said.

A gallery spokeswoman told Fairfax Media in March that the AGNSW represents the views and artistic practices of the entire state.

"The Gallery is actively engaged with Western Sydney through its exhibition program, loans from its collection, education initiatives and collaborative meetings with leaders and cultural partners from across Western Sydney," she said.