The Berejiklian government approved the lease to 19th-century Campbell's Stores warehouses in The Rocks in 2017.

The government then announced that leaseholder - private hospitality company Tallawoladah - would fund a $32 million refurbishment of the warehouses, which are the only of their type remaining on the Sydney Cove foreshore.

Once the overdue renovations are complete, the warehouses are expected to house 12 restaurants, cafes and bars.

NSW shadow treasurer Ryan Park wants Treasurer Dominic Perrottet and predecessor Gladys Berejiklian to say who approved the lease.

He says unlike the long-term lease of heritage sandstone government buildings on Bridge Street, the Campbell's Stores site did not go to a public tender.

"If there is nothing to hide here then the premier and Mr Perrottet must stand up and reveal the nature of the deal and the contract," Mr Park said in a statement on Thursday.

"What independent oversight of this secret arrangement was there?"

Property Minister Victor Dominello and Tallawoladah have been contacted for comment.

The warehouses, owned by the Sydney Harbour Foreshore Authority, were added to the state heritage register in 2002.

The register says the buildings are the surviving element of a complex of wharves and stores that began in 1801 when Robert Campbell constructed Australia's first privately owned wharf.

Australian Associated Press