A foreign out-of-hours doctor who killed a pensioner with a painkiller overdose on his first and only shift in Britain remains at risk of repeating the "grave" error, a disciplinary panel ruled today.

Nigerian-born Dr Daniel Ubani injected David Gray, 70, with 100mg of a pain relief drug - 10 times the recommended dosage.

Mr Gray, who was suffering from kidney stones, died at his home in Manea, Cambridgeshire, a few hours after he was given the massive overdose of diamorphine on February 16 2008.

Dr Ubani, 67, a specialist in cosmetic medicine based in Witten, Germany, admitted causing the pensioner's death after confusing the morphine with another drug.

He was given a nine-month suspended sentence in Germany for death by negligence but still works a doctor in that country, the General Medical Council panel heard.

The panel ruled today that Dr Ubani's fitness to practise was impaired because of his misconduct in treating Mr Gray and two other patients on the same shift.

It will now discuss what sanctions, if any, should be taken against him on his registration to practise in the UK. Dr Ubani, who could be struck off, is likely to learn his fate tomorrow.

In its ruling, the panel said: "The panel has grave concerns about Dr Ubani's clinical competence.

"The panel has concluded that Dr Ubani's actions on 16 February 2008 presented a significant risk to patients as he failed to recognise and work within the limits of his own competence.

"It was unacceptable to prescribe and administer a controlled drug, diamorphine, with which he was not familiar.

"As a clinician, it was Dr Ubani's professional responsibility to ensure that he was familiar with the drug that he was prescribing. If he had any doubts, then he should have sought advice from colleagues.

"The panel also concluded that Dr Ubani's actions have brought the profession into disrepute and breached a number of the fundamental tenets of the profession. Dr Ubani made several prescribing errors, both in terms of drugs prescribed and in terms of dosage chosen.

"He failed to keep his medical knowledge up to date and made a number of serious clinical errors."

It added that it had concerns about the doctor's insight into his failings.

Dr Ubani did not attend the hearing in Manchester and sent an email to the GMC saying: "I shall not be attending said hearing. I feel it should not serve any positive purpose."

The panel noted: "While Dr Ubani accepted his error with the diamorphine and apologised for it, the panel is of the view that his response failed to demonstrate acceptance of his other failings and little evidence of insight.

"The panel has received no evidence from Dr Ubani that he has fully acknowledged his deficiencies or attempted to remedy them.

"Given Dr Ubani's limited insight, the panel has formed the view that it is highly unlikely that he has remedied his deficiencies.

"Furthermore, the panel is satisfied that there remains a risk of Dr Ubani repeating such actions in the future."

It added that the doctor's conviction for causing death by negligence also impaired his fitness to practise.

Dr Ubani cannot now be tried in a criminal court in Britain because of double jeopardy laws.

The GMC also looked at Dr Ubani's treatment of two other patients on the same day - Sandra Banks, 59, who was given the wrong medication for a migraine, and Iris Edwards, 86, who was found dead in her care home a few hours after he treated her.

Dr Ubani had flown into the UK the day before and only had a few hours' sleep before starting a 12-hour shift, the panel heard.

He was working for SuffDoc, part of the out-of-hours GP service provider Take Care Now, for £45 an hour.

The evening before he started the shift, he was given several hours' training on the firm's computer system at its headquarters in Colchester, Essex, the hearing was told.

He was also given an induction by a doctor, who gave him a sheet listing all of the available drugs and for which illnesses to administer them.

That doctor expressed concerns that Dr Ubani had no experience of working for the NHS, did not know the area, and that he did not have enough time to properly train him.

But his report was not read until two days after Mr Gray's death.

The vials of medicine given to Dr Ubani were all the same size - 10mg - except for the diamorphine, which was in a 100mg tube, the panel heard.

Before visiting Mr Gray, Dr Ubani went to the home of Ms Banks, who was suffering from a migraine.

He injected her with painkillers, which made her condition worse, and left the syringe in her bedroom.

She was later taken to hospital in an ambulance after her condition deteriorated, the panel heard.

After seeing Mr Gray, Dr Ubani went to visit Ms Edwards at her care home in Ely, Cambridgeshire.

She was not sent to hospital even though her heart was racing and she had low blood pressure, and she later died of a heart attack.

A coroner recorded a verdict of natural causes as it was unclear if she would have lived had she gone to hospital.

The GMC Fitness to Practise Panel concluded that he made "recurrent mistakes" with all three patients.

"In particular, and most significantly, Dr Ubani prescribed medications for each patient which were not clinically indicated, and in three instances the doses were inappropriate," the panel said.

"In the most serious of these, the error resulted in the death of DG (David Gray).

"The panel is of the view that this single negligent act of prescribing and administering a fatal dose of diamorphine was particularly grave.

"In addition, the panel has also found that Dr Ubani repeatedly failed to take an adequate history, to make an adequate physical assessment and to make adequate medical notes of his consultations.

"Dr Ubani demonstrated a worrying pattern of basic clinical errors and misjudgments in all three consultations. In these circumstances, the panel has concluded that Dr Ubani's actions amount to misconduct."

Dr Ubani specialises in cosmetic surgery and anti-ageing treatments and is believed to have been practising medicine for 23 years.

At the conclusion of the inquest into Mr Gray's death, Cambridgeshire North and East Coroner William Morris said the doctor was "incompetent" and ruled that Mr Gray was unlawfully killed.

He said his death amounted to gross negligence and manslaughter.

Mr Gray's family have recently accepted £40,000 compensation from sources which remain confidential as part of the payout agreement.

They have also lodged a complaint with the European Court of Human Rights against the German and UK Governments over the handling of the criminal inquiry into the death, a spokeswoman for Anthony Collins Solicitors said.

Cambridgeshire Police, who were investigating Mr Gray's death, issued a European arrest warrant for Dr Ubani to bring him back to the UK to face a possible manslaughter charge.

But, as the warrant was issued, it emerged that legal proceedings had already been instigated in Germany.

At a court in Witten, the doctor pleaded guilty to causing death by negligence - a lesser charge. He was given a nine-month suspended sentence and ordered to pay 5,000 euros (£4,300) costs.

The prosecution, which is allowed under German law, means he cannot be extradited to face charges in the UK.

The family, including Mr Gray's sons, Stuart and Rory, who attended the Manchester hearing, claim the handling of the criminal inquiry was a violation of their human rights. If their claim is upheld they could claim compensation from both governments.

Success at the court could also see the German government overturn Dr Ubani's conviction, which would allow him to be charged with corporate manslaughter.