Senior doctors and unions say health spending needs to rise by $700 million in this week's Budget.
The Association of Salaried Medical Specialists and the Council of Trade Unions say operational spending in health needs to rise by $700 million in Thursday's Budget, on top of extra spending already flagged.
They said their analysis showed that was the level of increase needed to retain current service levels and keep pace with the demands of a growing and ageing population with complex health needs.
The association's executive director, Ian Powell, said a much lower funding increase was expected in Thursday's Budget.
"The indications are a lot less than that, based on some leaked documents, and if that's the case then we are going to have a public hospital workforce under increased stress.
"It already is under stress, and the government has an obligation to reduce that stress, not increase it."
Mr Powell said documents obtained by the Labour Party show the increase in funding could be more like $340m.