London ? Britain is facing a sperm donor shortage after reversing confidentiality laws and limiting the number of women who can use sperm from one donor, fertility experts warned Wednesday.

Britain in 2005 changed the law protecting anonymous sperm donors and allowed children to learn the identity of donor fathers – one reason, fertility experts say, there are fewer donors now.

“The only countries that seem to have enough sperm are those that pay – like the U.S. and Spain – are the countries that retain anonymity,” said Allan Pacey, a member of the British Fertility Society that warned of the shortage in the British Medical Journal.

“In the countries that have removed anonymity … there seems to be a problem,” he said.

In 1991, Britain logged 503 sperm donors, according to figures from the Human Fertilisation and Embryology Authority. In 2000, there were 325, and in 2006 – the year after the law was changed – the number dropped to 307.

Experts say 500 donors a year are needed to cope with the number of couples needing donor insemination in Britain.

Dutch authorities have also put out calls to encourage sperm donors after scrapping anonymity for donors in 2004.

“There is a shortage of sperm donors. This is because of the new laws that make the anonymous donation of sperm impossible,” the University of Amsterdam’s Fertility Clinic of the Academic Medical Center said on its Web site.

Usage limits could also affect availability.

In Britain, only 10 babies can result from one donor – a limit some have called arbitrary.