The opening has been set back to 2020 because of ventilation problems in the critical care facility, which could cost an extra £90m to rectify.

An independent review of the governance of the project by KPMG has found that the main issue with ventilation in critical care stemmed from an error in a document produced by NHS Lothian at the tender stage in 2012.

Documents issued to bidders stated single bed cubicles and four-bed rooms in the critical care ward required a ventilation system with four air changes per hour. But the relevant guidance requires 12 changes per hour for this type of ward.

The bid race for the non-profit distributing PFI-style contract was won by Multiplex-led IHS Lothian consortium with a target date to open in July this year.

But days before the opening serious problems with the ventilation system were uncovered during tests by an independent contractor.

The Scottish Government said it would now parachute in a senior programme director to take responsibility for day to day delivery of the Royal Hospital for Children and Young People from now until the site is fully occupied.

A new national body – Programme for Government – will also be created to have oversight for the design, planning, construction and maintenance of major NHS Scotland infrastructure developments.

The KPMG report attributes this to human error and confusion over interpretation of standards and guidance. It also concluded that opportunities to spot and rectify that error were missed.

Scottish health secretary Jeane Freeman said: “I am of course bitterly disappointed that a mistake made in 2012 was not picked up earlier.

“This is a publicly funded project of strategic importance, which has not been delivered by NHS Lothian in compliance with the standards and guidance.

“The delay we now face will be borne by NHS Lothian staff, by patients and their families and the additional cost will be to the public purse.”