The health watchdog has been forced to take action against a hospital trust in East Anglia which performed a surgery on the wrong patient.
Monitor says that within a month, Cambridge University Hospitals NHS Foundation Trust performed four botched surgeries at Addenbrooke's Hospital.
They included leaving instruments inside two patients and performing surgery on the wrong person.
Surgeons also operated on the wrong part of the body of another patient. The trust says it's determined to improve.
– Jane Ramsey, Trust Chairman
We take Monitor's concerns very seriously and we are determined to reverse the situation as soon as possible...
"We will be setting up a task force to swiftly get back on track. We will be focusing on turning this trust around, so once more we can be justifiably proud of our record as one of the leading trusts in the country.
We are treating more people than ever before and our health outcomes are amongst the best in the country.
"Our priority remains the care of our patients - they are at the heart of everything we do."