The Scottish Health Secretary has said she overruled NHS Lothian over plans to open a new children's hospital next week.
Jeane Freeman said she needs to be assured that the new facility in Edinburgh is safe in all respects.
Patients, staff and services at NHS Lothian's Royal Hospital for Sick Children were expected to transfer to the Royal Hospital for Children and Young People on Tuesday of next week.
READ MORE: New Edinburgh Sick Kids Hospital opening halted just hours before move
But it was announced on Thursday that Ms Freeman has postponed the move after final checks revealed the critical care department's ventilation system does not meet national standards.
An investigation has been ordered into how the hospital got to such an advanced stage before the failings were discovered.
Ms Freeman told BBC Radio Scotland that she was informed about the issue with the ventilation system on Tuesday.
Asked who made the decision not to go ahead with the opening next week, she told the Good Morning Scotland programme: "I did, and I did that entirely for patient safety for two reasons.
"One, of course, is critical care needs to be safe, it needs to meet national standards. You can't have an emergency department if you don't have critical care.
"But also, because this was picked up so late, I want to be assured that all other safety checks in the rest of the hospital are also conducted again independently and that they meet national standards too."
The Health Secretary said NHS Lothian had been looking at a range of options to resolve the difficulty, such as having a partial opening or a work-around in terms of critical care.
"But the decision I took was that that was too great a risk," she said.
"I need to be sure that every other area of that hospital meets the national standards, is safe, before I will then agree that aspects of it can open."
Asked whether she had "overruled" NHS Lothian over the opening plans, she told the broadcaster: "Yes I have".
Ms Freeman said she wants to find out why the health board was so confident that the hospital was meeting the required standards "when, self-evidently, in critical care, it certainly wasn't".
She added: "I've also instructed an audit of every single aspect of safety checking - who signed it off, what was the governance of that - so that I can identify where has the mistake been made here and what went wrong, so that we can then deal with that."
She said there is no indication at this point that any fault lies with the contractors themselves.
Ms Freeman spoke of hopes of seeing a phased introduction of services into the new hospital once the results of the safety checks are in.
She continued: "On the ventilation system itself, work is under way to identify what upgrade is needed, where we can source that from, what additional work inside critical care is needed in order to put in the upgraded ventilation system.
"At the end of all of that, I will know how long that will take. That is likely to take months, rather than weeks, but that's just about critical care and the emergency department."