The state government has been accused of sneaking through plans to privatise the operation of a further five hospitals across the state.

More than $1 billion was committed at the last state election to upgrade hospitals at Maitland, Wyong, Goulburn and Shellharbour and for improvements at a fifth, in Bowral.

The government confirmed on Thursday that under its plans private companies would be invited to submit tenders to build and run the hospitals, but said public patients would continue to receive free care.

Health minister Jillian Skinner said the state government was ensuring the sustainability of the health system.