In a letter to staff, Northern Health chief executive Greg Pullen said job losses could be another consequence of a $107 million reduction in federal funding for Victorian hospitals this financial year.

Mr Pullen said Northern Hospital would have to cut $4 million from its budget over the next six months and reconsider opening the additional operating theatre in February.

''It will also mean that waiting lists will increase, beds will have to close and we may need to shed some jobs,'' he said.

Northern Health director of surgery Neil Strugnell said the new operating theatre was needed to treat a growing number of patients requiring emergency surgery.

''People with a life-threatening bleed, ruptured spleen or needing a caesarean section will get done immediately, but people who have surgery that needs to be done within 12 to 48 hours often experience delays of several days while they wait for access to an operating theatre,'' he said.

Dr Strugnell said the extra operating theatre had been ready to go for more than a year but its opening had been delayed due to a lack of funds.

''The Northern Health board had made a decision to open the theatre in February. However, the whole thing is in jeopardy because of this federal government clawback,'' he said.

Dr Strugnell said the emergency theatre could treat up to 10 patients a day when operational, improving surgery access for emergency patients and reducing cancellation of elective operations.

The $107 million funding cut for Victorian hospitals this financial year follows an adjustment by the federal government based on new population data from the 2011 census.

Victorian Health Minister David Davis said the data showing Victoria's population had grown 0.03 per cent was flawed, and other data showed an increase of 1.4 per cent.

The adjustment means that Victorian hospitals have to pay back $40 million from last financial year and weather a $67 million cut this financial year.

Federal Health Minister Tanya Plibersek said the major driver of the adjustment was the changing price of healthcare, and it was in line with the national health agreement signed by governments last year.

A Northern Health spokesman said the organisation that also includes the Broadmeadows and Craigieburn health services, was examining cost saving measures including extending Christmas bed closures.

He said a $4 million reduction in Northern Health's budget for the rest of the financial year ''could equate to 50 full-time positions or 1000 elective surgery cases'', and changes would have to be made from January.

Dr Strugnell said the federal government's reliance on 0.03 per cent population growth was hard to reconcile with growth in Northern Health's catchment.

Ms Plibersek is due to meet hospital board chairmen in Melbourne on Wednesday.