Bishop John Buckley has spoken out strongly against legalising the practice after the Health Service Executive (HSE) confirmed the lecture by Professor Len Doyal at Cork University Hospital.

Gardaí adopted a discreet presence in the vicinity while private security at the hospital was stepped up.

The lecture by Prof Doyal, who is a proponent of voluntary and non-voluntary euthanasia, had already sparked outrage, with MEP Kathy Sinnot describing it as "sinister".

Bishop Buckley said human life is a precious gift to be loved and defended in each of its stages.

"There is no such thing as a worthless human life. The Lord alone is the giver of life and He alone has the right to decide when that life should end. It is always gravely wrong to deliberately end or destroy a human life," the bishop said. "Euthanasia is the deliberate ending of a human life before its natural end."

Bishop Buckley said people expect doctors and those in the medical profession to heal and save lives, not to end them.

"Euthanasia undermines the relationship between patients and their doctors and those in the medical profession," he said.

"Those who are sick, frail and elderly deserve our particular care and respect. Pope John Paul, with his own painful witness in his own suffering, showed the world every day that all life has a value and is worth living."

His comments were made at the opening of a new home for the Irish Sisters of Charity in the diocese Wednesday.

The bishop thanked and praised the sisters for their work in Cork, particularly their care for the sick and the dying at Marymount Hospice at St Patrick’s Hospital.

The chairman of the CUH Ethics Forum, Dr Fergus Walsh, said: "The purpose of inviting Professor Len Doyal, a noted expert in the field of medical ethics, was never intended to cause offence or worry.

"The Ethics Forum wishes only to promote an active discussion about this controversial ethical and legal issue in medicine."

The lecture took place yesterday in CUH at 5pm in the main auditorium.