Privatisation of the Lands Titles Office by the South Australian Government will put the jobs of about 200 employees at risk, the Public Service Association (PSA) has said.

Expressions of interest for a 40-year lease to run the titles and valuation services closed back in January, and the privatisation is due to be in place by September.

PSA official Nev Kitchin said the union did not want the change to happen because of the impact for the workers involved.

"There are currently about 230 staff involved and we believe that, on the basis of the draft organisational chart that we've seen, that would mean effectively 200 staff would be displaced overall from the existing Lands Titles Office and from the valuations area," he said.

"They will either need to take a separation package or they will need to find alternative positions in government.

"Or they would need to transition to the new employer and, in doing so, we would have real concerns that their conditions of employment may be diminished."

The PSA, Law Society, Institute of Surveyors, Institute of Conveyancers and SA Real Estate Institute all oppose privatisation because they say the Lands Titles Office is among the most efficient government agencies.

No final decision by Cabinet

The State Government said Cabinet was yet to take any final decision and unions and other interest groups were being consulted throughout the process.

The Government said it would continue to set fees and charges and ensure consumer protection if the functions were privatised.

Acting Premier John Rau says any current staff affected by changes would be offered other positions.

"If they are not required by the Government in that function and are not offered an opportunity elsewhere then those people remain employees of the state and the state has obligations to those people which the state would fulfil," he said.

A privatisation is expected to boost SA Government coffers by about $400 million.

Australian Conservatives MLC Dennis Hood said the latest move followed state privatisations of Forestry SA and the Motor Accident Commission.

"Very major assets are being sold off, or planning to be sold off in the case of the Lands Titles Office, which the public's had no say in," he said.

"There was no talk of selling off the Lands Titles Office before the last election.