An aesthetic doctor currently serving 4½ years' jail for drugging and molesting a male patient has been struck off the medical register and will no longer be able to practise on his release from prison.

Tan Kok Leong, in his mid-50s, had admitted to his conviction to the disciplinary tribunal of the Singapore Medical Council (SMC).

But he "declined to plead guilty as he wished to maintain his position that he was innocent of the charges", according to the grounds of decision issued by the SMC this week. He had also said through his lawyers that he would not contest the charges.

On July 5 and 6 in 2013, Tan gave his patient, a Malaysian doctor, a sleeping drug in the course of a liposuction procedure in a hotel room at Oasia Hotel. He molested the man and took more than 20 lewd photographs.

He was found guilty of molesting the 33-year-old man and sentenced to 3½ years' jail in 2016. His jail term was increased to 4½ years in 2017 after the prosecution appealed.

In its decision, the tribunal said the case was unprecedented in terms of the serious nature of the charges, the brazenness with which they were committed, and the penalties imposed by the High Court.

"It is axiomatic that patients place their bodily and physical integrity in the trust and care of their treating physician," the tribunal said.

"Any breach of this trust brings irreparable harm to the reputation and good standing of the medical profession as a whole.

"It follows that any medical practitioner convicted of a sexual offence in relation to a patient should, by that very act, be considered to be unfit to practise in this hallowed profession," it added.

In mitigation, Tan's lawyer said his client was active in charity work, including removing tattoos for former prisoners under the Yellow Ribbon Project. Tan claimed to be a pioneer in the field of liposuction and some of his patients and fellow doctors had given him positive character references.

His lawyer argued that "the circumstances of the offence were highly exceptional and had to be weighed against his achievements in the course of a distinguished career", and asked for a two-year suspension.

The tribunal noted that removing a doctor's name from the register is the most severe penalty and not one to be imposed lightly. "The conduct must be of a nature that is inimical to the fundamental mission of the medical practitioner," it said.

However, given "the degree of depravity involved", the tribunal felt that its decision was justified.

Tan had not only "detained the patient without his permission for two days, and manhandled him at his whim and fancy in the most degrading manner", but also took photographs.

"It cannot be over-emphasised that had the images found their way to broader circulation on the Internet, they would have caused incalculable harm to the reputation and dignity of the patient," it said.

"The inherent risk involved in such voyeuristic photography is therefore a clear aggravating factor," it added.