The suspension of children's heart surgery at a Leeds hospital was "premature" and could put a massive strain on services across the north of England, a body representing health workers has said.
The British Congenital Cardiac Association questioned the accuracy of data that led to the decision to halt children's congenital heart operations at Leeds General Infirmary.
All operations were halted on Thursday after NHS figures suggested the unit had a death rate double that of other centres. However, Dr Tony Salmon, president of the British Congenital Cardiac Association, said he was not aware of any centres having a higher than expected mortality rate.
He said relevant data has been compiled by the Central Cardiac Audit Database (CCAD) for the past 10 years, adding: "We are very concerned that some of this preliminary 'raw' data, which has not been verified, has entered the public domain before CCAD or any of the hospitals have had an opportunity to assess or ratify the information.
"CCAD must be given the opportunity to examine, audit and correct the data before any conclusions can be drawn about mortality, including risk stratified outcomes, in Leeds or indeed any of the UK centres.
"As a result of the fact that the data has not undergone stringent checks, the suggestion that there is a higher than expected mortality rate in Leeds or any other centre, is premature."
Following the suspension of surgery, Sir Bruce Keogh, the medical director of NHS England, said the figures were among a "constellation of reasons" the decision was made. However, doubts have already been cast over the reliability of the mortality figures.
Elspeth Brown, consultant cardiologist at Leeds Teaching Hospitals NHS Trust, has claimed the figures for Leeds were "incomplete", with more than a third of cases missing. Just 180 operations out of more than 300 in the unit were considered in the figures, she said.
Professor Sir Roger Boyle, director of the National Institute of Clinical Outcomes Research, which oversees mortality data across the NHS, said further analysis which included the missing cases still showed a "gap" in mortality rates at the hospital.
Dr Salmon said: "It is a matter of urgency that the events in Leeds that resulted in the temporary suspension of paediatric cardiac surgery and intervention are understood and resolved. The clinical fallout of ceasing surgical and catheter interventions, even for a short period, could lead to acute under provision of services in the North of England. Resolution of the current crisis in Leeds is now critical."