Chief Minister and Health Minister Katy Gallagher said she had frozen $41 million budgeted for the design work of a new block to replace the 10-storey tower at the Canberra Hospital.

But dozens of extra public beds could be opened at Calvary Hospital in Bruce after administrative staff were moved off-site.

Ms Gallagher had also called a halt on plans for a new sterilisation facility at the hospital after being advised of a potential multimillion-dollar budget blow-out.

In response to questions from Opposition Leader Jeremy Hanson during an Assembly committee hearing, Ms Gallagher said she was considering whether design work on the new Canberra Hospital tower should go ahead.

She said it might be more appropriate for the government to focus on expanding services at Calvary Hospital and constructing the new 200-bed sub-acute hospital planned at the University of Canberra.

She said she had delayed the tower project because she was not convinced it should go ahead at this point in time.

The new tower block would be home to some of the most important parts of the Canberra Hospital.

"This is the biggest phase of the redevelopment,'' Ms Gallagher said.

''It is the wards, the operating theatres, the intensive care unit. Replacing the existing tower block will be the new state-of-the-art tower block.''

Outside the committee room, she said the new block would have to be built eventually but there might be more immediate priorities for allocations from a limited capital works budget.

"In a sense it will be easier to have more beds go to Calvary and the northside hospital before we focus on working on areas of core services at a tertiary hospital,'' she said.

Beginning work on the new tower would hit the government's budget bottom line by $90 million because the value of the old building would have to be written down.

If the tower block project was delayed, a new emergency department would have to be built.

A final decision would need to be made on whether to delay the project before the budget was brought down in June.

Health Directorate infrastructure chief Grant Carey-Ide said more ward space had been created at Calvary by moving some administrative staff away from the site. Other staff from Calvary and the Canberra Hospital had moved to the old emergency services headquarters site at Curtin.

"We have been able to free up space for approximately 50 beds at Calvary Hospital because we supported the relocation of some 80 administrative staff from the main hospital campus to a facility on Thynne Street at Bruce,'' Mr Carey-Ide said.

All of Calvary's private wards are due to be taken over by the public system within five years. A new private hospital is planned for the Calvary campus.

Ms Gallagher told the committee she had halted work on the new sterilisation facility after being advised the $18 million budget could blow out to $25 million.

"Not good enough,'' she said.

The project was being reviewed and it was possible sterilisation services would remain in Mitchell.