A doctor has been given a formal warning after he was cleared of intentionally hastening the death of a patient with a large dose of diamorphine.

Dr William Bassett admitted he injected 100mg of the drug into the 65-year-old man but the General Medical Council alleged he did so in a moment of stress so the lung cancer sufferer could "die in peace".

However, a medical disciplinary panel has ruled it was a genuine mistake and that Dr Bassett could have easily covered up any deliberate wrongdoing.

The GP, based at the rural Brown Clee Medical Practice in Ditton Priors, Shropshire, informed his manager and health trust bosses about the circumstances shortly after the death of the patient in May 2009.

The hearing in Manchester was told that nurses who had been caring for the patient reported the incident as they believed it was a "serious departure" from the end-of-life care standards.

The matter was referred to West Mercia Police and Dr Bassett gave a prepared statement in which he said he had injected the full dose "accidentally" due to the fact he was "struggling".

He said he had not intended to inject the full contents of the syringe and he accepted he did not give any thought to trying to reverse the effects of the overdose but that he believed what had happened was "in the best interests" of the patient.

The hearing was told that the dead patient's family had no grievance with Dr Bassett and did not wish to take part in the proceedings.

In finding - on the balance of probabilities - that he did not hasten the death, panel chairman Dr Surendra Kumar said it was "likely" no-one would have known what had happened but for Dr Bassett's honesty in reporting the incident.

He said: " It (the panel) considered that it would be inherently unlikely that if you had deliberately injected the patient with an overdose of diamorphine that you would have told anyone.

"The panel has borne in mind that you did not seek to hide the fact that you had given a large dose of diamorphine to the patient. It has noted that it would have been easy for you to do so."

He continued: "The panel found you to be a credible witness giving as best an account of what happened as you could. Having taken account of your good character, the panel has determined that, it is more likely than not, that you would have told the truth to this panel.

"In addition, given the material regarding your good character, it is unlikely that you would have done what has been alleged. The panel considered that such action would be manifestly inconsistent with the ethics and morality that you have been shown to have."

The panel said that Dr Bassett usually used 10mg and 30mg ampoules of diamorphine but none were available on the day in question and it was impractical to obtain other quantities because of the secluded location of the practice.

He had intended to inject 20mg but despite his intentions injected 100mg by mistake Dr Kumar said the error was "so serious as to be considered deplorable" and it amounted to misconduct.

However, the panel concluded his fitness to practise was not impaired and decided to issue a formal warning on his registration.

The warning will be published on the List of Registered Medical Practitioners (LRMP) for a period of five years and will be disclosed to any person enquiring about his fitness to practise history.

At around 1pm on May 29, Dr Bassett made his fourth visit to the terminally ill man in 24 hours.

The patient was very "unsettled and frightened" by his illness, the GMC said.

The hearing heard that in his notes, Dr Bassett said it was a "large dose but he is dying and I would like him to die in peace".

Later in his notes, the doctor described telling the family about what he had done.

He said they discussed the high dose of morphine and were "told honestly what morphine did, ie) hasten death".

The notes also said: "Family accepts this."

The GMC called in an expert to review the evidence who found that the 100mg administered was between six and 10 times greater than he would have expected to see.

The expert also said Dr Bassett gave the injection "at a time when his judgment was affected by a distressed patient and his family, stress from overwork and tiredness due to an interrupted night's sleep on the previous night".

Giving evidence, Dr Bassett said there was "a lot of tension in the room" as the family were in tears and three family members were holding the patient down on the bed.

He told the panel that even now he could not be sure how the mistake occurred but he would never knowingly have approached the patient with the whole 100mg of the drug.

When he realised there was nothing left in the ampoule he said his "heart dropped" and he was "shameful".

He told the panel he would never seek to bring about someone's death and that "life is very important and you should not hasten death even by a second".

The panel concluded there was no evidence to suggest Dr Bassett had behaved in a similar manner previously or since.

Dr Kumar said; "It is clear that you care for your patients. The authors of the testimonials, amongst other things, described you as 'diligent', 'hardworking', 'conscientious', 'highly professional', 'outstanding', 'an example to all' and 'an asset to the medical profession'.

"The authors speak not only of your providing excellent clinical care to your patients but also describe your character, honesty and integrity as being beyond reproach.

"The panel accepts that you have fully appreciated and reflected upon the gravity of your error and that you have shown genuine contrition for this. The panel has noted that you have used this experience as a learning exercise for yourself and others.

"The panel also considered that you will have learnt a salutary lesson not only from these proceedings and the potential consequences for your career as a medical practitioner, but also the potential for extremely serious criminal charges."

No criminal charges have been brought against Dr Bassett as an inquest is set to take place into the patient's death at a later date.