Paediatric heart surgery has been suspended at the John Radcliffe Hospital in Oxford after four recent deaths.

Oxford Radcliffe Hospitals NHS Trust, which runs the hospital, has now launched an investigation with its internal inquiry being monitored by the independent health regulator The Care Quality Commission (CQC).

The fatalities happened during procedures over the past three to four months and involved “very sick children” all with congenital heart problems.

Each case will be reviewed. Meanwhile, urgent cases are now being transferred to other hospitals though other cardiology procedures at the hospital will continue as usual.

In a statement, the Trust said: "We have temporarily suspended the paediatric cardiac surgery service while we investigate concerns that have been raised.

“The families of children awaiting cardiac surgery are being contacted and we will be placing those patients who need to be seen urgently with other hospitals.

“This is high-risk surgery and the trust is taking the right steps in conducting this review. We are reviewing each of these patients to ensure that they are not put at risk by any delay in their treatment.”

Roger Davidson of the CQC said it was reassured that the trust had taken action to ensure the immediate safety of patients.

It is not clear how long the trust’s investigation will take but the entire treatment process for patients will be examined.

In 2007 the hospital was criticised for its death rates among adult heart patients and had earlier been investigated by the Healthcare Commission over deaths during coronary artery bypass graft procedures.