Image copyright CBC Image caption A lawsuit alleges Dr Norman Barwin used his sperm to impregnate at least two of his fertility clinic patients

A Canadian medical regulator has formally revoked the licence of a retired fertility doctor who used his own sperm to inseminate patients.

The College of Physicians and Surgeons of Ontario called Norman Barwin's actions "beyond reprehensible".

The regulator launched an investigation into allegations against him in 2016.

The claims against the physician date as far back as the 1970s and include patients from at least two fertility clinics in Ontario.

Speaking for the regulatory body's disciplinary panel in Toronto on Tuesday, Dr Steven Bodley said it was "unfortunate" the only sanction they had the power to impose was to revoke Dr Barwin's licence and issue a scathing public reprimand and a fine.

"You betrayed [the trust of your patients] and by your actions deeply affected individuals and their families and caused irreparable damage that will span generations," he said.

Now 80 years old, Dr Barwin did not appear before the disciplinary panel and was represented by a lawyer. He has not practised since 2014.

What are the allegations against Dr Barwin?

According to a statement of facts released by the college, it documented 13 cases where Dr Barwin had either used his own or unknown sperm to impregnate his patients.

Dr Barwin's lawyer pleaded no contest to the statement of facts on his behalf.

Image copyright BBC News Image caption Senior counsel for the College of Physicians and Surgeons of Ontario, Carolyn Silver

Carolyn Silver, acting as prosecutor for the college, called Dr Barwin's actions an "inexcusable deception".

"[His] shocking actions will leave an indelible stain on the profession," she told the panel during Tuesday's hearing.

Dr Barwin was previously sanctioned by the college in 2013 for artificially inseminating three patients with the wrong sperm and received a short suspension.

The regulator launched the most recent investigation when a lawsuit was filed that alleged that 50 to 100 children were conceived after their mothers received the wrong semen from Dr Barwin and that 11 were genetically matched to the fertility doctor.

None of the allegations in the lawsuit have been tested in civil court.

What did his victims say?

The panel heard impact statements from four of Dr Barwin's victims.

Rebecca Dixon, whose family is currently suing the doctor, said her "whole identity was called into question" when at age 25 she learned that Dr Barwin was her biological father.

Image copyright Courtesy of Rebecca Dixon Image caption The Dixon family learned that Daniel was not Rebecca's biological father.

The Dixons contacted Dr Barwin in 1989 to help them get pregnant and Rebecca was born a year later.

Ms Dixon said the idea that Dr Barwin was her biological father "repulsed me - it made me feel contaminated".

She said the impact of his actions is embedded in her DNA and is something she will one day pass along to her children.

Ms Dixon says she has discovered 15 half siblings since learning about her biological background.

Another patient of Dr Barwin - whose identity is protected by a publications ban - discovered that an unknown donor's sperm, and not her husband's, had been used to inseminate her when she sought Dr Barwin's help conceiving.

"I felt violated - dirty - almost as if I had been raped," she said of learning she had been inseminated with a stranger's genetic material.

One father, whose identity is also protected, described the feeling when he learned his children are not related to him as "a quadruple punch in the gut".

"Imagine the slow torture of watching my children grow up looking less and less like me," he said.