Robert Borsak, of the Shooters, Fishers and Farmers Party, also questioned whether the museum's director Dolla Merrillees had the sufficient skills and experience to deliver a new museum as she told a parliamentary inquiry that the cost of the controversial project was unknown.

Mr Borsak, the chairman of the inquiry, said that secrecy surrounding the proposal to relocate the museum raised serious concerns.

"You may understand the vision," he told Ms Merrillees. "We do not see it. We do not know anything about it. The land is subject to Parramatta River flooding."

Mr Borsak added: "How can we have any confidence at all that what is being proposed is going to meet the requirements?"

Mr Borsak said the Powerhouse Museum (rebadged as the Museum of Applied Arts and Sciences) covered 8.3 acres at its current Ultimo site, but the proposed new site in Parramatta on the former David Jones car park was only 2.4 acres.

"From my review of having been out to the site I cannot see how it is the same, or at least only 3000 square metres less, unless you are talking about a high-rise building," he told an inquiry hearing last week.

Mr Borsak later asked: "Ms Merrillees, as a long-standing professional museum director, do you ask this committee to believe that you can squeeze the enormous objects currently on display at Ultimo into the footprint at the new site at the Parramatta car park?"

Ms Merrillees said finding space for the museum's large items was under examination.

The at-times fiery hearing was called to hear further evidence from Ms Merrillees and Professor Barney Glover, the chairman of the MAAS board.

Ms Merrillees admitted the cost of building a new museum and moving its collection from Ultimo to Parramatta, a distance of approximately 20 kilometres, was unknown.

The inquiry has previously been told the project could cost up to $1 billion.

"Do you still believe that your experience is sufficient to envision, direct and control such a large and complex project?" Mr Borsak asked Ms Merrillees.

Ms Merrillees said she believed she had the skills required, as did her staff and board of trustees.

She also told the inquiry some of the permanent exhibitions at its Ultimo site had not been changed for "probably about 30 to 35 years".

The parliamentary inquiry, set up in June, has been dominated by the state government's controversial proposal to move the Powerhouse Museum to Parramatta and sell off its Ultimo site to developers.

But the inquiry is also examining government funding for NSW museums and galleries, the impact of the efficiency dividend on institutions' budgets and the plight of museums in regional NSW.

Labor's Arts spokesman Walt Secord said there was community concern about "a cloak of secrecy" over the Powerhouse relocation.

Mr Secord clashed with Professor Glover over secrecy surrounding the amount of taxpayer-funded overseas travel taken by museum staff.

He also raised the spectre of the NSW government not proceeding with the museum move following policy backflips over West Connex and banning greyhound racing.

Professor Glover said he believed the government remained committed to moving the Powerhouse to Parramatta, subject to the final business case and acquiring the new site.

But under questioning from Greens MP David Shoebridge, he said the MAAS board would only support the move if there was sufficient funding to build an improved museum and the new site was not compromised by other commercial developments.

"The board would express its serious concern to government if we felt those conditions were at risk, yes," Professor Glover said.