It is the third known case in the Netherlands of a doctor using his own sperm without patients' knowledge or consent.
A former Dutch gynaecologist used his own sperm in at least 21 fertility treatments, an investigation has found.
Joe Beek -- who died in 2019 -- was found to have impregnated women without their consent between 1973 and 1986.
A hospital in the city of Leiden -- where he was worked as a specialist for 25 years -- confirmed the findings on Tuesday.
It is the third known case in the Netherlands where a gynaecologist used his own sperm in fertility treatments without consent.
The investigation was launched by the Alrijne centre in Leiderdorp, which was formerly known as the Elisabeth hospital.
'Dozens' of possible descendants
The hospital confirmed that they had been approached last year by FIOM, a Dutch paternity organisation representing 21 children.
Under a 2004 law, Dutch citizens aged over 16 have the right to know the identity of their biological parents. It was later established by DNA that all 21 children in question had the same biological father.
"It appears that this doctor donated his own sperm and used it to inseminate expectant mothers waiting for sperm anonymously," the hospital said.
"There is no record that the children and their parents were aware of this," it added.
The clinic did not confirm how many patients Beek had treated during his tenure at the hospital and said all archives have been destroyed.
The hospital has appealed for anyone who was treated by the gynaecologist to contact them and said they could not rule out "the possibility of discovering dozens of descendants".
'We are very shocked by this'
An independent investigation into the matter was commissioned in January and is expected to be published next summer.
"The way this doctor acted at the time is unacceptable," said Peter Jue, a board member of the Alrijne centre.
"We are very shocked by this, it of course has a significant impact on the parents and children involved," he added.
The hospital has added that fertility treatments were hardly regulated during the 1970s and 1980s and stressed that the situation is "completely different now".
In October 2020, DNA tests revealed that a gynaecologist -- who died in 2009 -- was the biological father of 17 children.
One year earlier, another doctor was found to have used his own sperm to father 49 children with unknowing patients.