A powerful union previously responsible for an aggressive campaign against the Baird government says it will spend up to $1 million in three months to campaign against plans to privatise the operation of five hospitals.

"We've resolved to spend up to $1 million by the end of the year," said Brett Holmes, the general secretary of the Nurses and Midwives' Association.

Brett Holmes, general secretary of the Nurses and Midwives Association, is concerned a US-style healthcare system is on the horizon. Credit:Ryan Osland

"Some people said there was no basis to our concern, but the more we see the running of hospitals handed to private operators, the more it seems we are headed to an American [health] system."

The state government unveiled last week plans to privatise the operation and building of five hospitals across NSW, including at Maitland, Wyong, Goulburn, Shellharbour and Bowral. Private operators will be invited to submit expressions of interest to run the hospitals.