A British man may have fathered up to 600 children through a fertility clinic that he founded.

Reports have stated that Bertold Wiesner, an Austrian Biologist, and his wife co-founded a fertility clinic in London in 1940, but that as much as two-thirds of the sperm samples that were donated were from Bertold himself; a practice which is outlawed today.

It was first brought to light by two men who were researching their background up to the date of their conception at the clinic.

Barry Stevens, a filmmaker from Canada, and David Gollancz of London looked at DNA records which suggest that Wiesner was in fact their father, according to reports from the Daily Telegraph.

The DNA tests were conducted on 18 people conceived at the clinic between 1943 and 1962. The results produced pointed to the fact that two thirds of those children were fathered by Wiesner.

The two men then used that research to produce an estimate of the total number of children that could have been fathered by Wiesner and found that around 600 of the children were Wiesner's.

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"A conservative estimate is that he would have been making 20 donations a year…Using standard figures for the number of live births which result, including allowances for twins and miscarriages, I estimate that he is responsible for between 300 and 600 children," Gollancz told the Sunday Times.

Allan Pacey, chairman of the British Fertility Society, said it is possible for a man to make enough donations to father that many children, but such an action is currently illegal.

Britain set up the Human Fertilization and Embryology Act in 1990 in order to provide oversight and regulations for fertility clinics.

Sperm donors can provide samples for the creation of up to ten families. Around 2,000 children are born every year in Britain with the help of fertility clinics.