The contractor was due to hand over the high-profile project next month but now this will be delayed for several months while the substandard cladding is replaced.

A spokesman for Royal Papworth Hospital said: “As an NHS Trust, we have a duty to uphold the highest safety standards for our patients and staff.

“As a result, Royal Papworth Hospital’s board of directors has taken the decision not to accept handover of the building until Skanska has completed remedial work in accordance with the trust’s original requirements. This will cause a delay to the opening of the hospital.

“The hospital is currently awaiting confirmation from Skanska with regards to how long this remedial work will take, but early indications suggest it will take a number of months. ”

In recent weeks, both Skanska and an independent tester have been checking the building to ensure it meets the specifications set out in the original contract.

During this period, Skanska informed the Trust that they had used insulation materials that did not meet original requirements in the lower part of the hospital building.

Stephen Posey, chief executive at Royal Papworth Hospital NHS Foundation Trust, said: “We are extremely disappointed that we will not be able to open our new hospital in September as planned.

“Our staff have been working extremely hard to prepare for the move, and it is incredibly frustrating to discover a problem with the building at this late stage. However, we must ensure that our new building meets our original requirements.

“We do not underestimate the impact that this news will have on our staff.”

A Skanska spokeswoman said: “We remain in discussions with the trust on this matter and we are working towards a resolution in order for the hospital to open as soon as possible.

“We share the trust’s aim to uphold the highest standards for patients and staff.”