Dr Moor's supporters expressed their delight after the hearing. A support group had held public meetings and gathered petitions in his support.

Fiona McAndrew, spokesperson for Friends of Dr Moor, said: "It's been a long hard slog but we really feel that our campaign when the charges were brought made a real difference to the outcome.

"His patients are absolutely thrilled that this man has been found not guilty. The case should never have been brought in the first place."

BBC Health Correspondent James Westhead: "Other doctors have admitted administering fatal doses"

Dr Moor's daughter, Joanne Moor said she was confident that her father would be acquitted.

She said: "I never really had any doubt, but there was always a small doubt in the back of my mind that the jury might not feel the same as me.

"I feel the tears of relief rather than tears of joy.

"It has been a traumatic time and hopefully my dad will now stick to horse riding and forget about everything else."

Dr Michael Irwin wants euthanasia legalised

Dr Michael Irwin of the Voluntary Euthansia Society said: "I am very pleased by this verdict.

"Many doctors have been concerned in the past 22 months since Dr Moor was first arrested because they could so easily have been there themselves.

"Dr Moor was responding to his patient's request - he wanted to relieve his suffering.

"To me, this not guilty verdict shows that slow euthanasia is alive and well."

Dr Michael Wilks says the law is unclear

Dr Michael Wilks, chairman of the British Medical Association's ethics committee, said the guidelines for doctors were not sufficiently clear, and he denied that the Moor case had significantly clarified the law around euthanasia.

He said: "We are no further along the road towards any change in the law on euthanasia.

"This case just tells us that doctors who take the law into their own hands, who intend to kill their patients, as it was originally thought that Dr Moor had, are likely to be prosecuted."

Pro-life campaigners concerned

Dr Michael Irwin and Dr Michael Wilks discuss the implications of the Moor case

But Human Rights Society secretary Jennifer Murray said: "I think this case has muddied the waters on this issue even more and could make patients very wary.

"We do not feel that there is any way to enshrine euthanasia in law as there can never be sufficient safeguards."

Dr Andrew Fergusson, chairman of the Healthcare Opposed to Euthanasia group, said: "I am deeply concerned that this trial will add to the considerable confusion among the medical profession and the general public about what is acceptable medical practice in the grey area between life and death."

He added: "This does not in any way legalise so-called mercy killings - it does not give the green light to the euthanasia lobby or to doctors who may be tempted to take the ending of patients' lives into their own hands."

Dr Peggy Norris, chairwoman of the anti-euthanasia group Alert expressed disappointment, saying: "I think this is a sad day for medicine as it makes the law unclear as to what is allowed.

"We cannot have a half-law when it comes to this.

"This myth is being put out all the time that the doctors walk a tightrope - I've never heard such rubbish in my life.

"We might as well say that the hospice people are walking a tightrope all the time.

"But they are treating their patients with confidence, the patients are comfortable, and there is no question that they are in any way deliberately hastening death.