A five-year-old girl who died during an operation in Oxford to remove her spleen had her aorta ruptured by a surgical instrument, a coroner ruled today.

The operation at the John Radcliffe last year was meant to cure Bethany Bowen's anaemia but she started bleeding through a tear in the vital artery and she died less than an hour later.

Oxfordshire assistant deputy Coroner Dr Richard Whittington, recording a narrative verdict, said that the fatal injury was caused during her surgery.

Dr Whittingham, recorded a narrative verdict at the inquest into the death of five-year-old Beth, of Cricklade, Wilts.

The surgeons carrying out the procedure were using a morcellator - a bladed coring device - that they had not used before.

But he said it seemed unlikely that a new device was responsible.

Bethany's father Richard Bowen has said he had little faith that lessons will be learnt from his daughter's death and the family is now threatening legal action.

Mr Bowen said there needed to be an independent body to monitor training.

"Despite the admissions of the trust prior to the inquest hearing, we have little faith that lessons will be learned until there is an independent body that monitors surgical training in the NHS, with real power to punish those that don't abide by the rules," he said.

"The risks that were taken by the trust during the operation on Bethany were simply incredible and the attitude of the trust was truly appalling.

"Until the NHS is called to account for taking these risks they will simply go on killing our children."

Paul Rumley, a clinical negligence specialist from Withy King, who represented the family throughout the three-day inquest, said the Bowens were disappointed with the verdict.

"They still maintain that the operation performed on their beloved daughter Bethany was not the one they consented to," he said.

"They still earnestly wish that the lessons from Bethany's tragic death are learned not just by this trust, but by all hospitals and surgeons operating in this field.

"To that end, Withy King will now be pursuing a clinical negligence claim against Oxford Radcliffe Hospitals NHS Trust on behalf of Mr and Mrs Bowen.

"The trust admitted, prior to the Inquest hearing, that it breached the required standard of skill and care in respect of Bethany's surgery and thereby caused her death."

A spokesman for the ORH said: "This was a very tragic case. We have met Bethany's family and apologised for the terrible outcome of this operation. The trust has also admitted legal liability.

"We investigated the circumstances of the death in great detail, and sought independent expertise to try to help us to understand what went wrong.

"It is not possible to say with any certainty what caused Bethany's death. An operation of this nature will never be without risk, particularly when carried out on such a young child.

"Although this will be no consolation to the family, we have learned from this tragedy and have put those lessons into practice."