A statement attacking the controversial Human Fertilisation and Embryology Bill was read out to parishioners across the country last week.
The briefing, prepared by the Catholic Bishops' Conference of England and Wales, warned that the Bill would allow the creation of "half human, half animals" by combining eggs of women with the sperm of animals.
It added: "To do this would be a radical violation of human dignity."
But scientists involved in animal-human embryo experiments accused the church of "blatant inaccuracy".
Dr Lyle Armstrong, of Newcastle University, said the church's statement was "a gross and irresponsible misrepresentation of our position and our intentions". Hybrid embryos were designed to provide stem cells to treat human diseases - not to create half-human, half-animals, he said.
He added: "We find their example of combining the egg of a woman with animal sperm even more distasteful and we wish to make it absolutely clear that our work does not involve this. We find it surprising and saddening-that the Catholic Church should resort to such blatant inaccuracy to support its message in these matters."
Under the Bill, which is going through Parliament, scientists would be allowed to create animal-human hybrids for medical research.
They would take an animal egg cell, remove the blob in the centre which contains most of the animal's DNA and replace it with the nucleus from a human cell, taken from a donor.
The resulting embryo is 99.9 per cent identical to the human donor - although it contains some animal DNA left over from the egg.
The Catholic Church has sent every parish a pack of information including the one-page briefing document which some priests have read to congregations.
Chris Shaw, Professor of Neurology and Neurogenetics, Institute of Psychiatry, King's College London, said: "The bishops' statement on hybrids is not a radical violation of human dignity as they claim - it is a radical violation of the truth."
A spokesman for the church said: "Far from providing misinformation in our parish briefing, all we have done is draw attention to what this Bill actually allows.
"Clause 4 allows licences to be given for the creation of hybrid and "interspecies" embryos, defined in the Bill as "an embryo created by using human gametes and animal gametes". This means half human and half animal."
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