The warning comes after scientists are the University of Bath used research on mice to prove how, in principle, viable embryos can be created from non-egg cells, such as skin cells.
Senior bioethics consultant at the Christian charity CARE, Philippa Taylor, said: "[The researchers are] not using eggs, so they have made a step beyond that but they are so far off creating anything beyond what is affectively a very young embryo."
A team led by molecular embryologist Dr Tony Perry, bypassed the normal process of fertilising an egg with sperm to produce healthy, fertile mice offspring.
Dr Perry said: "Our work challenges the dogma, held since early embryologists first observed mammalian eggs around 1827 and observed fertilisation 50 years later, that only an egg cell fertilised with a sperm cell can result in live mammalian birth."
Underlining how significant obstacles would need to be overcome before reproduction without egg cells is technically feasible, he added: "This is speculative - it's entirely speculative and fanciful."
Philippa Taylor from CARE added: "I would have huge ethical concerns about a whole range of issues around this, like the whole business about manipulating and playing around with embryos.
"Of course, the media headlines are wanting to sell papers and it sounds very real and likely but if scientists aren't careful and if they overhype too much, the public become more and more sceptical and then it makes it harder from scientists in the longer-term when they have genuinely good research."
Pictures are for illustration only