Health Secretary Jeane Freeman postponed the opening of the Royal Hospital for Children and Young People in Edinburgh last month.
She overruled the board at the last minute and made the decision amid concerns about ventilation and drainage.
Recently she was asked if she could give a guarantee that the hospital will be open in either 2019 or 2020 – a response that has been branded “astonishing”.
However, Ms Freeman said it would not be fair to staff or patients to speculate before the reviews she has ordered have been completed.
She said: “It wouldn’t be fair to the staff or patients affected by this delay for me, or anyone else, to give guarantees before we have the facts from the reviews I ordered in July. Anything at this stage is purely speculation.
“That timetable of work I set out last month, when issues with the ventilation in critical care came to light, is on track.
“Work by Health Protection Scotland and Health Facilities Scotland is well under way and will give me the information I need to base any future decision about a timetable for the move to the new site.” The hospital has been marred by disputes between the board and Integrated Health Solutions Lothian, the consortium responsible for designing, building, financing and maintaining the hospital.
Ms Freeman also announced last month that various investigations would be undertaken on governance and what went wrong.
And although these internal NHS reviews are expected to be completed by September, Ms Freeman has not given any indication of an opening date for the hospital.
It is not known if NHS Lothian did not provide her with accurate information.
Ms Freeman added: “I’ve asked KPMG to independently review the governance arrangements for the new children’s hospital to establish the factors that led to the delay.”
She also declined to back NHS Lothian chief executive Tim Davison, who leads the embattled board behind the new-build.
Labour MSP Monica Lennon said: “It is worrying that she has no idea if the hospital will be declared safe to open next year in 2020. This is astonishing and shows how badly this project has been managed.
“Every single day that this hospital lies empty is wasting money that could be benefiting patients.
“It’s a disgrace and Scottish Labour demands an independent public inquiry.”
Tory MSP Miles Briggs said: “SNP ministers and NHS Lothian are both equally responsible for this unimaginable fiasco and have completely failed to explain how these problems are going to be fixed.
“Jeane Freeman increasingly looks like a rabbit caught in the headlights, unable to provide even the most basic information to families and NHS staff on the potential opening date for the new Sick Kids.”
Last week, trade union official Tam Waterson claimed that drainage is a bigger issue than the ventilation concerns.
He said: “We know the drainage is not fit for purpose. It’s been flooded twice with nobody in it. There is a school of thought that they might have to rip it down.”