Supporters say limited cloning could help treat killer diseases like AIDS while opponents argue the freedom to manufacture embryos in a laboratory opens an ethical minefield on the cutting edge of modern science.

The two competing visions will face off as early as this week if backers of "therapeutic cloning" push a vote in the UN General Assembly that will spell out society's willingness to take the task of creation into its own hands.

Costa Rica, the United States, the Philippines and more than 50 other nations, backed by the Vatican, want a worldwide convention banning all forms of human cloning by next year.

Their proposal says the cloning of human beings is "morally repugnant, unethical and contrary to respect for the person and constitutes a grave violation of fundamental human rights."

Lined up against them are Belgium, Britain, China and a sizeable minority of other nations which believe limited cloning "opens up prospects for the improvement of the health of individuals and mankind as a whole."

Supporters of therapeutic cloning say their proposal safeguards the sanctity of human life but gives countries the latitude to police themselves and decide individually where the boundaries should lie.