Victoria's Opposition leader John Pesutto says whistleblowers have unveiled "savage cuts" to the health system proposed by the government.

According to Mr Pesutto, hospitals across the state are bracing for funding cuts which he said could result in job losses and the closure of services. 

"We know now through whistleblowers that the Allan Labor government is requiring health services to make savage cuts and they have only given them three weeks to do it," Mr Pesutto said.  

"This will mean job losses, it will mean service cuts right across the board and it will mean Victorian patients will pay the price."  

Ambulance Victoria is also grappling with the impacts of cost pressures, according to the Victorian Ambulance Union. 

"The ambulance service and the health system are under enormous pressure and can't afford to make any cuts to spending," union secretary Danny Hill said. 

"Even so-called 'back of house' cuts to areas like administration or Human Resources has a flow-on effect to frontline services not getting support they need at a time when they need it most." 

A letter seen by the ABC was sent to Ambulance Victoria staff on Friday by its chief executive Jane Miller.

"Health expenditure is a major cost driver for every government, with increasing demand and the growing cost of healthcare delivery placing enormous pressure on health budgets," she said in the letter.

"Ambulance Victoria is no exception." 

She went on to say the government would continue to fund the organisation to deliver services but its costs had grown.

"I need to be very clear that there was no budget cut to Ambulance Victoria in the recent State Budget," she said. 

"But we are operating well above our budget envelope and this needs to be addressed." 

She flagged "tough decisions" would need to be made but said senior leaders and cost centre managers would actively be involved in the process. 

Shadow Minister for Health and Ambulance Services Georgie Crozier criticised potential cuts. 

"They're asking hospitals to do more with less," Ms Crozier said.

"Going back to pre-COVID funding levels is a cut." 

Ms Crozier said the cuts would not only affect metro hospitals but impacts would be seen across the state. 

"When patients go to a hospital they need to be seen and yet the government is forcing these cuts on our small rural and regional hospitals that will force amalgamations," she said. 

When asked if some hospitals would be forced to merge as a result of these budgets, health minister Mary-Anne Thomas said "no, absolutely not". 

Ms Thomas would not, however, comment on whether or not there would be any job cuts to the sector. 

"Right now my department is in the process of finalising those budgets for the upcoming financial year," Ms Thomas said. 

"We are in the midst of a process of negotiating with our health services." 

She said said the negotiation process took place every year and the government was investing an additional $1.8 billion of funding to health services in the next financial year.