Staff members of Finance Minister Victor Dominello have been interviewed by police over the alleged leaking of personal information relating to a speeding fine incurred by the Opposition Leader's wife.

Last month, Labour leader Michael Daley threatened legal action over an article published in the Sydney Morning Herald claiming his office phoned a "secret hotline" to transfer a speeding fine into his wife Christina's name.

Mr Daley blamed the article on a "Liberal Party dirt unit" and said he was reporting the matter to police as a breach of privacy, because the details had been leaked from confidential records held by Revenue NSW.

Police have now confirmed officers from the Financial Crimes Squad are conducting inquiries into the leak and have interviewed a number of staff in Mr Dominello's office.

Mr Dominello issued a brief statement confirming his office had been contacted by police and was "assisting them with their investigation".

The ABC understands Mr Dominello himself was not interviewed as part of the investigation.

Revenue NSW, which manages the payment of fines, sits within the Department of Finance, Services and Innovation.

Michael Daley said his wife Christina was driving the vehicle at the time. ( ABC News: Philippa McDonald )

The SMH article quoted "records from the hotline" that showed calls were made by Mr Daley's office on August 3, 2017.

The call pertained to a car owned by Mr Daley that exceeded the speed limit by 10 kilometres per hour while driving through Banksmeadow in May that year.

In response to the reports, Mr Daley's office said a staff member had contacted NSW Revenue but denied it was via a "secret hotline".

At the time Mr Daley confirmed his wife was driving his vehicle and the fine arrived in his name.

He said he filled out a statutory declaration that his wife was the driver.

"Liberal Party dirt units are now trawling through departments' websites," Mr Daley said at the time.

"And now the details of personal citizens — supposedly held under privacy laws — are finding their way into the newspaper."

Mr Daley declined to comment about the police investigation.