It comes amid growing calls from property and legal experts for the government to terminate its sale of the land titles registry - a "reckless" move that they believe led to the error.

Opposition finance spokesman Clayton Barr moved a motion last week to allow a debate about the "horror" bungle, but this was refused.

He said, based on talks with Land and Property Information (LPI) staff, the government's decision earlier this year to split it into five units and let go of 70 employees caused the error.

"It is a fact the member of LPI staff responsible for following up on errors within the Central Register of Restrictions (CRR) was made redundant as at June 30 this year in preparation for privatisation," he said

"It is a fact that there is no designated person currently following up on the registration errors that occur."

Finance Minister Dominic Perrottet last month revealed that between July and October, the CRR responded to 309 enquiries with wrong information. Now, 204 families have homes that could be flattened for a future F6 freeway, and one property will be acquired for a tunnel.

He has apologised for the "simple administrative error", deploying door-knocking teams and commissioning an independent investigation.

In response to Labor's accusations, Mr Perrottet said: "If Labor's priority is to irresponsibly play politics at every opportunity with an issue that affects peoples lives, and to pre-empt an independent investigation, that is a matter for them."

"My number one priority is making sure the families affected have the information and support they need."

He would not say whether the investigation results would be made public nor whether the government would reconsider its decision to privatise the register.

Mr Barr's assertions about the LPI employee responsible for the error reflects what land titles and legal expert Margaret Hole understands occurred. She is against the privatisation of the natural monopoly.

"Information has been provided to us from reliable sources the person(s) responsible for the entries into the CRR were involved in 'voluntary' redundancies and, amongst the ensuing chaos, there was apparently no one to pass the baton to," said Ms Hole, a former president of the Law Society of NSW.

"It is clear that under the prior efficiently administered unit it would have been effectively resolved and correct entries made and notices given, which is the reason that an omission of this critical task has never happened before," she said.

She is concerned about the lack of transparency of the sales process, public consultation and independent analysis.

The government paid JP Morgan $4.5 million for the scoping study, which it won't release because it is "commercial in confidence". It wants to spend the proceeds - possibly $2 billion - of the 35-year concession on building sports stadiums.

Don Grant, surveyor-general of NSW from 1986 to 2000, said there had never been an error like the F6 bungle in the registry's 150-year history.

He said it was world class, profitable and efficient. It is based on Torrens Titles, meaning each Certificate of Title is backed by a government guarantee.

"I've worked in 20 odd countries to introduce land titles reform and they're all envious of what we have in NSW," he said.

"Privatisation can occur in certain areas, but when it's an economic pillar for the state, it is reckless. The government has had an attack of madness, to be quite honest."

Tim McKibbin, chief executive of the Real Estate Institute of NSW, said while it is open-minded about privatisation, the LPI should remain in public hands.

"The system is very good and everybody has a lot of confidence in it. I'm nervous about starting to fiddle with something that is working very well," he said.

"The F6 bungle is one example of the litany of things that can go wrong if the registry system as it stands now isn't maintained. So, if we get it wrong, there will be very, very expensive outcomes."

Treasurer Gladys Berejiklian has argued the private sector is best placed to invest in new technology, leading to big benefits for consumers.

She said prices of regulated services will only go up by CPI, the state government will retain full ownership of the data, and it will have strong step-in powers

"These safeguards will ensure the integrity of the system and will protect the data collected by LPI," she said.

Interested buyers submitted their expressions of interest by October 31. Ms Berejiklian said the property bungle had "no impact whatsoever" on the sale process.

While potential bidders, which include infrastructure funds, Hastings, The Carlyle Group and Macquarie Infrastructure and Real Assets, declined to comment on the impact of the mistake, the government should expect some "tough questions" from buyers, sources have told the AFR.

"It's a terrible look. The errors could suggest 'systemic errors' and the LPI data room should expect tough questions in the due diligence," a source said.

Do you know more? ehan@fairfaxmedia.com.au

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