LONDON: Britain's parliament backed yesterday the creation of human-animal embryos which some scientists say are vital to research cures for diseases but critics argue pervert the course of nature.

The vote means Britain retains its status as a world leader in stem cell research. Human-animal embryo research is banned in some countries including Australia, France, Germany and Italy.

Parliament defeated an amendment to ban inter-species research - in which human DNA is injected into cells derived from animals - by 336 to 176 after hours of impassioned debate on ethics versus science.

The human fertilisation and embryology bill prohibits the transfer of the embryos to a human or animal and says they cannot be used for research beyond 14 days.

Prime Minister Gordon Brown supports the creation of human-animal or "admixed" embryos but some Roman Catholic members of his government oppose the research.

"If we want to sustain stem cell research and bring new cures and treatments to millions of people, I believe admixed embryos are necessary," Brown said.

Politicians were allowed to vote according to their conscience on this aspect of the bill rather than along party lines.

The bill, which updates 1990 laws, is at committee stage when amendments are tabled and will be subject to a final vote in coming weeks.

Two groups of British-based scientists have already been given permission to create human-animal admixed embryos. The bill legalises their research within set guidelines.

Some researchers say allowing admixed embryos would open more avenues as they seek cures for conditions like motor neurone disease or Parkinson's.

They say their creation would help resolve a deficit of donated human eggs, a barrier to embryonic stem cell research.