British scientists have applied for permission to produce embryos that would be 99.9 per cent human and 0.1 per cent animal
A major relaxation of IVF rules was announced by ministers today.
The changes will make it easier for single people and lesbians to receive fertility treatment on the NHS.
The move, which is part of a shake-up of laws on the use of human tissues, will also allow the creation of " Frankenstein" embryos - human and animal cells mixed together - for medical research.
Under current laws, fertility clinics have to consider the baby's need for a father before providing treatment. But today's draft Human Tissue and Embryos Bill says this is no longer necessary.
The draft legislation bans couples from choosing the gender of their child. It also tightens the law on screening embryos for diseases, a subject of heated ethical debate as it could lead to parents aborting potentially unhealthy babies and see insurance companies refusing people with a genetic illness.
Permitting the use of hybrid embryos for medical research is a major Uturn by ministers.
Initially, the Government had come out against Frankenstein embryos, fearing a backlash from religious groups. Health Minister Caroline Flint said today she been persuaded by the arguments from the Science communities and MPs.
Under the proposed laws, scientists will be allowed to create human-animal chimeras - human embryos that have been mixed with animal cells.
Sir David King, the Government's chief scientific adviser, said he welcomed the move: "I believe that the approach to the creation of embryos containing human and animal material is the right one."
Dr Stephen Minger, director of King's College Stem Cell Biology Laboratory, said: "This research is important because these stem cell lines could help us to understand what goes wrong in catastrophic neurological disorders like Alzheimer's disease and Parkinson's disease."
Pro- life groups have reacted with anger to the draft bill. Josephine Quintavalle, of the campaign group Comment on Reproductive Ethics, said: "It is appalling that the government has bowed to pressure from the random collection of self-interested scientists and change its prohibitive stance.
Ms Flint defended the Government's change in attitude towards hybrid embryos saying medical advances had allowed "us to get in the place where we are now".
She said all the proposals would be subject to scrutiny by a joint parliamentary committee before being introduced as a bill.
Other measures in the draft legislation include:
• Banning couples from choosing the gender of their baby.
• Couples in same sex civil partnerships should have equal rights as parents in traditional marriages.
• The regulation of internet sperm services.
• Tightening of laws on screening embryos for genetic diseases.
• Allow donor conceived children to find out if they have donor conceived siblings.
The Government is also recommending a change to the rules over the use of frozen sperm and the issue of withdrawal of consent.