THE public spending watchdog has been urged to investigate the unsafe £150m sick kids hospital in Edinburgh amid warnings it may have to be “ripped down”.

The Scottish Tories have written to Audit Scotland asking for a probe into the troubled project after a senior trade union official said its drainage systems may not be fit for purpose.

The hospital’s opening was cancelled at the eleventh hour last month over ventilation problems.

SNP health Secretary Jeane Freeman intervened after alarms were raised about the critical care unit at the new Royal Hospital for Sick Children and Young People at Little France.

It emerged last week that NHS Lothian is still having to pay the private consortium behind the hospital £1.4m a month for the unused building.

Now the Herald on Sunday has reported damning criticism from Tam Waterson, chair of Unison’s Scottish health committee, which represents 12,500 members in NHS Lothian, including staff who were expected to switch from the existing Sick Kids in Edinburgh.

READ MORE: SNP Health Secretary could have to resign over hospital scandal, says trade unionist

He said senior health board staff were "alerted to shortcomings in the drainage" more than 18 months ago, but the hospital was erected regardless.

He said: “People are unable to confirm whether the drainage that has been put in, is in fact fit for purpose. We need to find out what's happening before everyone moves in. We can't wait to find out later on and just keep our fingers crossed."

He added: "There is a school of thought that they might have to rip it down.

"How do you fix drainage in a building when it's X number of feet beneath the building? I'm not an engineer, but it's not going to be easy. I'm extremely worried."

Mr Waterson also called Ms Freeman "the worst cabinet secretary I have ever experienced".

The hospital is being paid for via the non-profit distributing private finance model supported by the Scottish Government through the Scottish Futures Trust.

The total contracted cost for consortium Integrated Health Solutions Lothian Ltd (IHSL) to design, build, finance and maintain the hospital over 25 years is £432m.

Tory MSP Miles Briggs said: “The new Sick Kids hospital was meant to provide world-class state of the art care facilities for children across Edinburgh and the east of Scotland.

“Instead, it’s been a complete farce from the start and, judging by these warnings, things could get even worse. The contract not just with the Sick Kids but the whole Little France has been an unmitigated disaster.

“This has unravelled on the SNP government’s watch, and it needs to start taking responsibility.”

He called for “full transparency around the project” and urged Holyrood’s Health and Sport Committee to undertake an enquiry into the project.

He said he had also written to Audit Scotland asking for “a full audit of the Sick Kids project and the contracts and specifications commission on the hospital”.

READ MORE: Revealed: NHS Lothian threatens consortium with legal action over troubled Sick Kids hospital

He said: “Jeane Freeman and the SNP Scottish Government management of this situation looks totally incompetent with the Health Secretary being blown along the road by the latest scandals and revelations on the quality of the construction.

“SNP Ministers need do get a grip and show some leadership. Children and families depend on it and deserve better than this.”

Scottish Labour’s health spokesperson also called for a public inquiry.

MSP Monica Lennon said: “We are learning more about the Edinburgh Sick Kids scandal by the day and now damning criticism of the Health Secretary from a leading trade unionist brings into question whether she can carry on.”

“It’s disgraceful that unions have been sidelined. It must be sickening for workers in our cash-strapped NHS to see millions going down the drain and no one is taking responsibility.

“Ultimately, the buck stops with Jeane Freeman. That the new Edinburgh Sick Kids could be ripped down before it even opens is unthinkable and a public inquiry must get underway.”

READ MORE: NHS Lothian in row over loan to consortium behind delayed children's hospital

Audit Scotland is due to issue its annual report on the NHS in Scotland in October.

A Scottish government spokeswoman said: "The health secretary has made clear that her greatest responsibility is the safety of patients, and for this reason decided to delay the move of patients, staff and services to the new hospital.

"Patients and carers have been contacted directly to confirm appointment arrangements and a dedicated helpline remains in place.

"She recognises that many staff share her frustration following the announcement of the delay."

The spokeswoman confirmed Ms Freeman will meet again with NHS Lothian staff representatives in the coming weeks.

Prof Alex McMahon, nurse director at NHS Lothian, said: "There are a number of independent reviews and investigations underway to verify and provide assurance that all aspects of the Royal Hospital for Children and Young People, the Department of Clinical Neurosciences, and Child and Adolescent Mental Health Services meet the appropriate standards before it becomes operational.

"The decision to delay the move followed the identification of a problem with ventilation in critical care. Given the pause in occupation, the commissioned reviews will focus on ventilation and will also look at drainage and water systems as a priority.

"An Oversight Board, made up of Scottish government, NHS Lothian, National Services Scotland and Scottish Futures Trust, has been established in order to provide co-ordinated advice on the readiness of the hospital to open and on the migration of services to the new facility. The reviews and subsequent reports will be provided to the cabinet secretary for health and NHS Lothian."