A British man who ran his own fertility clinic may have fathered up to 1,000 children using his own sperm.

Dr Bertold Wiesner set up the Barton Clinic with his wife Dr Mary Barton in the 1940s.

The London clinic became controversial after it announced only a small number of highly intelligent men would be accepted as donors. It claimed to use donors only from the middle and upper classes, including "peers of the realm".

Geoffrey Fisher, the then Archbishop of Canterbury called for the clinic to be shut down and a peer in the House of Lords denounced it as “the work of Beelzebub”.

Close friends from the couple’s academic circles provided sperm, but a shortage of donors is believed to have led to Dr Wiesner providing the majority of samples - unbeknownst to his wife.

Dr Barton told a 1959 government forum on artificial insemination: “I matched race, colouring and stature and all donors were drawn from intelligent stock.”

She added: “I wouldn’t take a donor unless he was, if anything, a little above average.

“If you are going to do it [create a child] deliberately, you have got to put the standards rather higher than normal.”

In 2001 it emerged neurochemist Derek Richter had fathered at least 100 children through his association with the clinic.

DNA tests carried out in 2007 on 18 people conceived at the clinic between 1943 and 1962 revealed two thirds of the group were Dr Wiesner’s children, the Sunday Times reported.

Now documentary maker Barry Stevens and barrister David Gollancz believe Dr Wiesner, who died in 1972, fathered at least 600 children at the clinic – perhaps even 1,000.

Stevens and Gollancz began investigating after research revealed Dr Wiesner was their biological father, making them half-brothers.

"A conservative estimate is that he would have been making 20 donations a year," Gollancz told the newspaper.

"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."

Stevens believes the figure is closer to 1,000, an astonishing statistic given the clinic was on record to have helped conceive up to 1,500 babies.

Dr Barton, who died in 1972, destroyed the clinic's medical records, leaving the offspring conceived there unaware of their blood ties and true family history.

Current guidelines on sperm donation in Britain say donors can be used for a maximum of 10 families.

This is limited because if the same donor was used to create so many children, there would be a risk that two of the offspring would unwittingly meet and begin a family of their own, risking serious genetic defects in their children, the Telegraph points out.