Britain's fertility watchdog is considering changing the rules to allow payments to people who donate their sperm, eggs or embryos to infertile couples.

The proposal - which will be part of a public consultation launched by the Human Fertilisation and Embryology Authority (HFEA) next week - will be controversial. At present, men who supply sperm or women who give eggs are allowed to receive only £15 and expenses for travel and time off work.

Critics are likely to claim the money could prove an inducement to men and women to make a decision they could come to regret - that of helping to bring a child who is genetically half their's into the world to be brought up by somebody else.

In addition, the process of egg donation is not easy and involves the woman taking potent drugs to stimulate her ovaries.

But altruism has not been sufficient to fill the demand. Eggs are in much shorter supply than sperm.

For women who cannot produce eggs, a donation is the only hope of bearing a child.

But a survey of the fertility clinics carried out earlier this year by the HFEA found that 90% were unable to meet demand, even though egg sharing - where a woman undergoing fertility treatment has her costs reduced in exchange for donating some of her eggs - has been permitted. The survey found that 38% of women had to wait between 12 months and 18 months for an altruistic donor to come forward, 8% waited between 18 months and two years and 17% waited more than two years.

Half the clinics in the survey could not meet the demand for donated sperm and there were difficulties in matching donors and recipients from certain ethnic groups. The clinics also reported an increased demand from single women and lesbian couples.

No recruitment strategy for sperm donors was particularly successful. Clinics reported putting adverts in newspapers and posters in universities.

Sperm and egg donation had been affected by the proposed legislation to end the anonymity of donors so their genetic children would be able to make contact in the future.

A voluntary register of adults conceived through donations was launched in April by Melanie Johnson, the public health minister.

The government has ruled that children born after next year will, when 18, have the right to know donors.

Few clinics use donated embryos, but the same problems of shortages and concern over the loss of anonymity apply, they said. A quarter felt payments for donors would help the situation and 30% felt the HFEA's public consultation should include that option.

Some of the clinics were opposed to increased payments, especially for egg donation, and the HFEA in its discussion document on the survey results highlights "the need to approach this ethically difficult area sensitively".

An HFEA spokeswoman said: "We need to ask the public what they think." She added the consultation on sperm, egg and embryo donation, which will be launched on Thursday, is part of the wider review of its powers and policies under the Human Fertilisation and Embryology Act that the authority has undertaken.