An investigation has been launched after the number of deaths at the intensive care unit (ICU) at Aberdeen Royal Infirmary was higher than expected.
Hospital chiefs believe an auditing error is responsible for the numbers.
Last year 150 deaths were expected in the ICU which would have given a mortality ratio of one.
Instead the figure was 1.2, making it the worst performing ICU in Scotland.
The actual number of deaths was not revealed.
A spokeswoman for NHS Grampian confirmed an investigation has been launched.
She said: “We have examined our audit process and believe there is a data entry issue which has contributed to these figures. We are working to resolve that error to ensure that these figures more accurately reflect patient data in the ICU in the future.
“We are also aware that there are often other complex underlying factors which may influence these figures and so in order that we can provide assurance to patients, relatives and staff, we have also commissioned a further external review of the data and the unit which will report shortly.”
Death rates at Aberdeen intensive care unit revealed as worst in Scotland