The health watchdog has demanded urgent action at a Brighton hospital after suspending some specialist operations.
The Care Quality Commission (CQC) undertook an unannounced inspection of the gastrointestinal surgery department at the Royal Sussex County Hospital in August after receiving concerns about its safety.
Several months before, The CQC had previously issued the hospital with a warning notice and told it to make improvements to surgery as a whole, with urgent conditions attached.
The full report, published on Thursday, reveals the CQC suspended upper gastrointestinal surgery at the hospital in August.
The gastrointestinal surgery department of the hospital is rated "inadequate" while the hospital as a whole is rated "good".
The inspection found gastrointestinal surgery wards were short-staffed, there had been an increase in patient falls and medicine errors due to staff tiredness, there were not enough cancer nurse specialists, and that senior medical staff "did not share a culture that was respectful or supportive".
Death rates in upper gastrointestinal surgery were found to be twice the national average - however, this figure "sat within the standard deviation confidence limits".
There were three upper gastrointestinal surgical consultants at the hospital - fewer than the four to six consultants required by the NHS.
Carolyn Jenkinson, CQC head of hospital inspection, said: "Following our inspection of surgery at the Royal Sussex County Hospital, I am concerned our teams have not seen any improvements, particularly in the upper gastrointestinal services.
"Despite issuing the Trust with a warning notice and imposing urgent conditions following our previous inspection, the lack of pace means we have taken action to suspend non-urgent upper gastrointestinal services surgery until we are assured the Trust can keep people safe.
"The Trust leadership need to take ownership of the issues they are facing by having far better governance and tackling the issues we have highlighted.
"Our inspectors observed nursing staff providing consistent, safe, dignified care. However, there were some who told us that because they were tired and didn't have enough time to monitor patients, they felt they were letting the people they care for down.
"We will reinspect to ensure improvements are being made and won't hesitate to take further action if needed to protect patients."
University Hospitals Sussex NHS Foundation Trust, which runs the hospital, said improvements have been made since the inspection four months ago.
Dr Rob Haigh, chief medical officer, said: "Since inspectors visited in August, we have been addressing their findings and made sure patients who required surgery received it at other hospitals.
"In September, we recruited a new specialist surgeon to bring staffing into line with recommended levels, and we are reorganising nursing activity to increase specialist care time for our patients.
"We also commissioned an external review that has provided us with the assurance that clinical outcomes for upper GI surgery from 2020 to 2022 were within the expected range.
"We continue to work with our staff, colleagues at Royal Surrey NHS Foundation Trust, the Surrey and Sussex Cancer Alliance, NHS and CQC, to help us resume the specialist service as soon as possible."