NHS watchdogs are to continue an inquiry into heart surgery at an Oxford hospital, despite publishing patient survival rates today which show no cause for alarm.

Surgeons at the John Radcliffe Hospital, in Headington, have welcomed the Healthcare Commission's move to post detailed statistics on its website, which show their performance falls within the expected range.

But they are angry that "spurious" statistics, collated by independent health information provider Dr Foster, prompted the commission to launch an inquiry last year.

Although the watchdog has admitted the new, risk-adjusted Central Cardiac Audit Database figures show all units and surgeons "are within or better than the expected range", it will not drop the Oxford inquiry.

Head of investigations Nigel Ellis said: "Previously published information has shown the unit has higher than average death rates for one type of operation. This CCAD data has been adjusted for risk and suggests the trust is within expected limits. Clearly, we need to analyse all of these facts, as well as other information, and consider whether there are any issues for the unit to address."

Surgeon Professor Stephen Westaby, who has worked at the JR for 20 years, said: "I'm pleased they're publishing these CCAD figures. They focused on coronary bypass operations with spurious figures obtained by Dr Foster. Dr Foster has a lot to answer for and in my view the mayhem they've created is a serious problem.

"Some Oxford surgeons have the best results in the world for very difficult procedures.

"We're actually doing extremely well, but most of what's said about us is not said by surgeons, but by organisations like Dr Foster.

"We operate way out on the edge here. If you operate on desperately sick people, then the risk is always going to be high. We don't turn down patients because they stand a chance of dying. My philosophy has always been that I'm here to try to help patients.

"If their only chance of life is a high-risk operation, I'm happy to do that, but because of the public scrutiny a number of surgeons are not so happy to do that."

The Healthcare Commission's review of the JR, due to be completed later this year, follows a similar investigation in 2004, into baby deaths during heart operations at the JR.

Staff argued the supposedly high mortality rates had been taken from statistics which were not risk-adjusted, to take into account factors like each patient's own chance of survival, based on illness or age.

The hospital was absolved of any shortcomings with the publication of the CCAD figures, based on statistics from individual surgeons.

When the commission launched its inquiry, JR managers called for CCAD rates to be publicised nationally. Spokesman Helen Peggs said: "For us, the publication of the CCAD figures is extremely important. We put our figures on our website, but it wasn't done nationally and we think it's what the public has wanted for a long time.

"We realise it does not invalidate the Healthcare Commission's investigation at the JR. We're hoping this will be something that's positive for us and them.

"It's already given them an insight into the way cardiac centres work and the difficulties of collecting data and risk-adjusting it."

Patients can see heart surgery survival rates at UK hospitals at heartsurgery.healthcarecommission.org.uk The website gives rates from all cardiac operations at 30 of the 33 units in England and Wales, with surgeons at 17 centres choosing to provide their individual rates.

The data gives overall rates, as well as the "expected range" of survival rates, according to factors like patient condition and age, which estimates the percentage of patients who should survive.