Concerns over mortality figures and fact that relatively junior surgeons left in charge of unit among reasons for suspension

Concerns that two relatively junior surgeons had been left in charge of surgery on children with congenital heart defects at Leeds General Infirmary were among a number of reasons behind the decision to suspend operations there, a key NHS adviser has said.

The hospital, which is engulfed in a row over the future of its children's heart services, is carrying out an internal review after data suggested a death rate twice the national average. The accuracy of the mortality figures has been questioned after it emerged that they preliminary and that scores of patients from Leeds had been omitted.

But Professor Sir Roger Boyle, the director of the National Institute of Cardiovascular Outcomes Research (Nicor), which oversees cardiovascular mortality data across the NHS, said the figures were among a number of reasons he advised that the unit should be suspended.

He told BBC Breakfast that concerns were raised that two relatively junior surgeons had been left in charge of the unit, which carries out around 400 heart operations on children a year. He was also aware of claims from the families of patients that their requests to be transferred to other units were ignored.

"I was aware last weekend of other concerns being raised about Leeds, concerns raised by distinguished surgeons who don't work in the area," Boyle said.

"Concerns raised by families through the Children's Heart Foundation that they weren't being given the opportunity to be transferred to other units when they'd requested that.

"And I was also aware a senior surgeon was away on holiday, another surgeon was suspended and that left the service being offered to the public by two relatively junior, local surgeons.

"To have two relatively inexperienced people holding fort, without the ability for any senior advice, is a precarious situation in my view.

"It's a question of experience and fine balance between being able to offer a safe service and one that is precarious."

Campaigners have reacted angrily to the suspension of operations, which was announced a day after a high court judge ruled that the hospital could carry on performing such procedures.

Doubts were cast over the early draft of mortality figures as it emerged that information from up to 150 cases had been omitted.

Dr John Gibbs, chairman of the steering committee for the Central Cardiology Audit Database (CCAD), which supplied the data, said he was furious that the figures had been leaked as they had not undergone the "usual rigorous checking process".

But Boyle, the government's former national director of heart disease, said further analysis including the omitted cases still showed similar results.

"In fact, the data has been reanalysed with these extra cases and we still see this gap in mortality rate," he said.

"I would not have been able to sleep this weekend knowing that there were people who might have been operated on in a potentially unsafe environment."

Boyle told the BBC Radio 4 Today programme it was pure coincidence that the suspension had come just a day after the high court ruling.

He said: "The email I had from my analysts appeared as the judge was giving her views in the royal courts of justice. It was pure coincidence.

"It is remarkable, but we had been working on this for over a year … trying to respond to the challenge of trying to separate out the hospitals on the basis of the mortality figures.

"The Safe and Sustainable review had to rely on a quality assessment of each centre and that was the point the judge found fault with."

Sir Bruce Keogh, the medical director of the NHS, defended the suspension, saying on Friday that it had had been taken for a "constellation" of reasons, including warnings from the Children's Heart Federation, which was concerned about aspects of decision-making at the hospital and had suspicions that staff "were not referring complex cases on to other centres with better expertise".

Keogh said there had been "rumblings" among the cardiac surgical community for some time that "all was not well" in Leeds.

Greg Mulholland, the Lib Dem MP for Leeds North West, said he was "stunned and appalled" by the suspension and called for Keogh to resign.

In a statement on his website, Mulholland said: "To have arrived in Leeds and done this, without warning, just one day after the decision to close the Leeds unit was proved in a court of law to have been unlawful, beggars belief.

"I believe that Sir Bruce Keogh should resign as he has both authorised this wholly unreasonable and deeply questionable action and also presided over the fundamentally flawed Safe and Sustainable review, which has proved an exercise in how not to effect major change to the NHS."

• This article was amended on 4 April 2013. The original called Nicor the National Institute of Clinical Outcomes Research, and said that it oversees mortality data across the NHS. Nicor is the National Institute of Cardiovascular Outcomes Research, and oversees cardiovascular deaths, not all mortality deaths.