A patient who received an organ transplant died after a surgeon failed to disclose that he had spilled the contents of a donor stomach.
The incident involved a surgeon from Oxford University Hospital NHS Foundation Trust.
An investigation by PA new agency found a lead surgeon accidentally cut the donor stomach but did not tell officials, and the incident was not recorded at the time.
Several organs became infected with Candida albicans, a type of fungal infection, and were then transplanted into three patients.
One recipient, a 36-year-old, died of an aneurysm caused directly by infection from the donated liver.
A second patient, a 25-year-old parent with children, became life-threateningly ill and needed their transplanted kidney removed.
A third patient, aged 44, who received a combined kidney and pancreas transplant, fell ill but subsequently recovered.
The incident only came to light after surgeons at Cardiff & Vale University Health Board raised the alarm with the Human Tissue Authority and the Welsh Government.
They became worried when the 25-year-old patient who received the kidney, and who was under their care at the University Hospital of Wales, became unwell due to the infected organ.
The patient, who does not wish to be named but is from South Wales, needed the donor kidney removing as an emergency. They were put in an induced coma and needed 16 blood transfusions. They also ended up on dialysis for more than a year, despite not having needed it previously.
A "serious incident" report by NHS Blood and Transplant - seen by PA - said the transplant surgeon from Oxford "had no recollection of anything of note during the retrieval", which took place in August 2015.
However, "upon reflection", he said a "small nick" had been caused to the donor's stomach during the procedure, and a "small volume of stomach content was spilt".
The spill was not documented at the time of the procedure, meaning those receiving the organs and their doctors were unaware of the risk of infection.
The NHSBT report concluded: "This incident represents an example of donor-transmitted infection with Candida albicans which contributed to the loss of one kidney graft and the death of a liver recipient. The infection of the graft may have arisen during the retrieval procedure."
The 25-year-old took legal action against Oxford University Hospital NHS Foundation Trust, where the surgeon is still employed, and the NHS has agreed damages of more than £215,000.
The trust admitted it had been in breach of duty of care by the failure of the surgeon to record the cut into the donor's stomach.
In defence of the legal action, trust lawyers claimed that, despite the stomach spill, even if known at the time of transplant, the risk would have been considered low.
But solicitor Jodi Newton, a medical negligence specialist at Hudgell Solicitors, representing the patient, said it was "a completely unacceptable breach of duty of care" which was "extremely damaging for patient trust in surgeons".
The patient who sued has now been left with life-limiting problems as a result of the mistake, including nerve damage linked to the removal of the infected kidney.
It is unclear whether the family of the 36-year-old who died or the 44-year-old are aware of the incident.
NHSBT said it was up to local transplant centres to inform patients about contamination.