IVF watchdogs have ruled out a scheme that would allow women to have cheap treatment if they are prepared to do it twice and donate half their eggs.
Cloning involves putting DNA from a donor into an empty egg
The Human Fertilisation and Embryology Authority (HFEA) says that "egg giving" means a woman risks her health by having extra treatment for financial reasons.
They have written to clinics forbidding them from setting up such programmes.
"Egg sharing", in which eggs from one treatment are divided between donor and a second woman, are safer, they say.
The ban does not affect "altruistic" egg giving - in which a woman gives up her eggs willingly when she does not undergo fertility treatment herself.
The HFEA was responding to fears from members of the public and clinics that egg giving plans were unethical.
At the moment, a single treatment cycle of IVF costs between £2,000 and £4,000 - and more than one is usually required.
There is a nationwide shortage of donor eggs which help women who have none of their own.
To solve this, some clinics offer couples who cannot afford to pay for IVF the option of cheaper treatment if they give up some of their eggs.
While the HFEA says that this is acceptable if the woman agrees to give up some of the eggs from each subsidised cycle she gets, it should not be allowed if the scheme involves the woman undergoing extra cycles to yield donor eggs.
This is because each cycle carries a small risk to the woman, because levels of her natural fertility hormones are raised artificially to stimulate the ovaries to produce more mature eggs.
Occasionally, if too much extra hormone is given, the ovaries can become over-stimulated - a deeply unpleasant and possibly dangerous complication.
The more cycles a woman undertakes, the more chance there is that during one of them, she will suffer some form of hyperstimulation.
Suzi Leather, the chairman of the HFEA, said: "There is a shortage of donor eggs in the UK and the distress of women who face long waiting lists for treatment is very real.
"However, the HFEA cannot allow clinics to offer a treatment where a woman, for no other reason than financial inducement, subjects herself to an unnecessary and possibly risky procedure."
An email telling clinics not to set up egg giving schemes was circulated this week.
Professor Ian Craft, at the London Fertility Centre, was one of those hoping to set up an "egg giving" scheme. The HFEA ban means this will not go ahead.
He told BBC News Online: "We believe that egg giving is as least as effective as egg sharing - perhaps more so.
"One of the features of the scheme we were planning was that the charges were completely transparent. Couples will go into this with their eyes open.
"Some clinics won't charge you for some aspects of IVF, but will charge you for other fertility treatments such as ICSI, and for the drugs you need."
He added: "You often need more than one cycle of treatment with egg-sharing."
"It would be very helpful for people who can't afford private treatment."
However, news of the ban was welcomed by Mr Sam Abdalla, director of the Assisted Conception Unit at the Lister Hospital in London.
He runs a successful egg-sharing scheme, and his own research suggests that donors have just as good a chance of getting pregnant as those who keep all their eggs.
He told BBC News Online: "I believe it's the right way to approach this issue.
"The donor is always given priority - if she produces only a few eggs, she can keep them all.
"But if she produces 10 eggs, she keeps five, and donates five."