After Professor Hwang failed to derive embryonic stem cell lines from more than 2000 human eggs, it is obvious that cloning human embryos will not be achieved easily. If it is to happen, an enormous quantity of hard-to-obtain eggs will be needed. British scientists, therefore, are calling for the creation of hybrid embryos made by inserting human genetic material into rabbit eggs. "We have to think about alternative sources of eggs," says Professor Chris Shaw, of King's College London. "The fertility of rabbits is legendary. There may be opportunities to use human cells for nuclear transfer to rabbit oocytes (eggs). Legally the position is not clear, but that's something we'd like to discuss with the HFEA (Human Fertilisation and Embryology Authority)."

Although Chinese researchers claim to have created hundreds of these hybrid embryos back in 2003, in no country has this procedure actually been legalised (although a government committee recently proposed it in Australia). "I think it is right to feel uncomfortable about creating some type of hybrid," commented Josephine Quintavalle, of the lobby group Comment on Reproductive Ethics. "The question is what would be created?' And I have suspicions of how useful it would really be for research."