NHS watchdogs will continue investigating heart surgery at an Oxford hospital despite publishing survival rates which show no cause for alarm.

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

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

Although the Healthcare Commission has admitted the new risk-adjusted Central Cardiac Audit Database (CCAD) figures show all units and surgeons "are within or better than the expected range", they will not drop their investigation.

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 fully analyse all of these facts, as well as other information, and consider whether there are any issues for the unit to address."

Cardiac surgeon Prof Stephen Westaby, who has worked at the John Radcliffe 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.

"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."