The NSW state government has been accused of “excessive secrecy” over the long-anticipated relocation of Sydney’s Powerhouse Museum to Parramatta, according to the Sydney Morning Herald.

Opposition to the already-contentious move is growing, as suspicion mounts around the transparency of the state government’s plans. The government has refused to release its business plan for the project, which has led to an upper house enquiry to be launched by Greens MP David Shoebridge and Robert Borsak of the Shooters and Fishers party.

The upper house inquiry has revealed that the relocation of the Powerhouse Museum could cost upwards of $1.5 billion, whereas the state government initial pegged costs to land around the $250-million mark.

The move also places the museum’s rich collection of rare artefacts at risk of destruction. According to Dr Lindsay Sharp, the Powerhouse founding director, 98 percent of the museum’s collection that is currently in storage would have to be unpacked, appraised, insured and repacked – a job for which Australia lacks sufficient cultural resources and expertise, he says.

Initially, the state government had promised to release a plan for the Powerhouse relocation project by March. However, they have now declared the plans to be in “cabinet confidence” – a move that led to the unlikely alliance between Shoebridge and Borsak, and the subsequent inquiry.

Speaking prior to hearings on Tuesday afternoon, Borsak expressed frustration at the government’s “excessive secrecy” and likened the situation to other recent political behaviour in the state, such as a similar lack of transparency over WestConnex.

Dr Sharp struck a similar tone to Borsak on Tuesday afternoon, telling Fairfax Media that the decision to relocate had been made “in haste and secrecy” by the former Mike Baird government, without adequate consultation. He claimed that the behaviour was symptomatic of a government that was ideologically driven by inner-city development.

When Gladys Berejiklian took over from Mike Baird as NSW premier in January this year, she seemed to be reconsidering her predecessor’s plans for the museum. However, after announcing two public meetings to discuss the relocation, she cancelled the second and announced that a new site had been arranged for the Powerhouse in a deal made with the Parramatta council. Months after it was promised, a business plan has yet to be made public.

Scant updates have been made on the progress of the Powerhouse project since Berejiklian confirmed the new location – the former David Jones carpark site – in July. Indicative renders were revealed in April and, if all goes to plan, the new Powerhouse site is expected to open in 2022.