The NSW government has been forced into a parliamentary debate on its controversial plan to move the Powerhouse Museum to western Sydney and sell off its Ultimo site.

The proposal will be debated in the NSW Legislative Assembly after opponents gathered enough signatures to force a parliamentary debate – a move that has been labelled a "stunt".

The Independent member for the seat of Sydney, Alex Greenwich, conceded the parliamentary debate, which is earmarked for February, could not halt the move.

"It seeks to hold the government accountable," he said. "They will have to reply on the floor of Parliament and really explain why they are seeking to move it and what their plan is for the relocation, which is something they haven't been able to do to date."

He added: "It's really unclear when it is going to be moved, where it's going to go to and how they are going to shift what is quite a major collection."

Mr Greenwich said the petition, which had gathered more than 10,000 signatures, supported the building of more museums in NSW.

"I would ideally like to see the Powerhouse stay where it is and they create an annex collection in western Sydney," he said.

He said many Powerhouse staff were opposed to the relocation and disappointed with the museum's trustees and outgoing director Rose Hiscock, who initially voiced opposition to moving the museum to western Sydney.

"I think people would have liked to see a more energetic opposition," he said. "I know a number of people internally within the Powerhouse Museum want it to stay where it is."

Co-founder of the Save the Powerhouse campaign, Patricia Johnson, said it was not possible to predict the impact of a parliamentary debate.

"However, what is certain is that it will raise even more public awareness of our fight to keep the Powerhouse Museum in Sydney," she said.

But deputy Premier and Arts Minister Troy Grant said western Sydney deserved a major cultural institution.

He pointed to a dramatic drop in visitors and school groups to the Powerhouse, which has also suffered declining sponsorship revenue and staff cuts.

"There is a growing abundance of cultural infrastructure in the CBD, with the government making significant investments in Walsh Bay and the Opera House while the Australian Museum and the art gallery are also working on big plans for the future," he said. "It's time some of this cultural infrastructure was shared with Western Sydney."

Selling-off the Ultimo site to developers is estimated to fetch $150-$200 million, which Mr Grant said will be spent constructing a new museum at one of two potential sites in Parramatta.

The Western Sydney director of the Sydney Business Chamber, David Borger, said it was possible the cost of moving the Powerhouse would exceed the value of the Ultimo site.

"There are lots of calculations on the backs of envelope but it may well be the new museum will cost more than the land value at Ultimo, that there will need to be additional contributions made."

The NSW government promised to spend $600 million on cultural institutions from the sale of electricity assets – earmarking $202 million to the Sydney Opera House and $139 million on refurbishing and creating new performance venues in Walsh Bay.

The new Powerhouse will compete for the remainder of the funds with several other projects including the proposed $450 million new wing of the Art Gallery of NSW.

"I certainly think western Sydney should be a priority because the bulk of those funds are going to worthy projects in the Sydney CBD," he said.

Borger called the petition a stunt by Mr Greenwich and Greens MP Jamie Parker to curry favour within their electorates.

"I don't think the petition is going to achieve anything. If you had a petition out here, you'd find an alternative view."