The UK's Human Fertilisation and Embryology Authority, which monitors screening standards in Britain, has advised against buying sperm by computer, saying it may not have been checked for HIV and other diseases.

The couple, known only as Jane and Sarah, contacted a company called NewLife on the internet. The company provides a matching service for infertile people, sperm and egg donors and surrogate mothers.

Those using the service pay a monthly subscription fee - at present there is a special offer of $12 a month - and fill in an electronic form, stating their personal details.

They also fill in details about the kind of donor or surrogate parent they want, including height, weight, income level, educational background, age and race.

Tall, dark and handsome?

The British couple from Winchester in Hampshire paid �280 for the sperm of a tall, dark 30-year-old man.

The women, a solicitor and teacher, have been together for six years and say they have tried every other avenue over the last three years.

Sarah, aged 32, says she has always wanted children, but after a miscarriage when she was 19 and several failed relationships with men, she thought she would never have a family.

After meeting Jane, a 27-year-old teacher, she felt her luck had changed. Jane will be inseminated by the sperm, which is being sent in frozen form by post.

Sarah said the couple felt artificial insemination was the best way for them. "It sounds very clinical and not at all how a child should be conceived in the traditional sense, but it is the most feasible option and we are grasping at the opportunity."

Screening

But the HFEA warned that internet donation was unsafe because sperm may not have been screened - as it is in recognised UK clinics.

Sperm and eggs can be ordered on NewLife's website

Spokesman Mark Salmon said: "On the Internet, women are paying a lot of money to have a tub of frozen sperm delivered to their door and then they have to thaw it out and inseminate themselves."

He said the HFEA did not discriminate against gay men and lesbians. The HFEA says that insemination at clinics is only around 9% successful and that home insemination is likely to be less effective.

NewLife denies it is exploiting women and says it keeps its fee at a "minimal" level to discourage people who are "not serious".

Donors are not allowed to know the name of the person buying their sperm or eggs. The service was started by Muly Litvak, a classical pianist and former officer in the Israeli army.