LONDON (Reuters) - Britain's leading scientific institution said Monday it is urging countries to back a campaign to stop a possible ban on stem cell research as part of a global treaty banning human cloning. The London-based Royal Society is stepping up its drive to push the United Nations (news - web sites) to ban the cloning of babies, but to make no ruling on using the technology for medical research, or therapeutic cloning, at its 59th General Session in October. The 191-nation U.N. General Assembly is divided over whether to allow therapeutic cloning to continue or to adopt a broad cloning ban championed by the Bush administration and Costa Rica with strong backing from the U.S. anti-abortion movement and many predominantly Roman Catholic nations.

Last year, the assembly put treaty negotiations on hold for a year after 66 scientific academies around the world expressed support for therapeutic cloning.

Cloning research relies on embryo cells, or stem cells, because they can grow into all types of cells and tissues in the body.

Supporters of a broad cloning ban argue therapeutic cloning, in which cells from human embryos are used in medical research, involves taking human lives because the embryos are eventually destroyed.

Although member nations would not be compelled to sign up to it, the Royal Society argues a treaty banning all forms of human cloning would place a major obstacle in the way of stem cell research which could provide new treatments for diseases including diabetes, Parkinson's and Alzheimer's.

"It is clear that if the convention bans all forms of human cloning, the UK, and other countries which currently permit carefully regulated therapeutic cloning, will not sign up to it," said Professor Richard Gardner, chairman of the Royal Society's working group on stem cell research and cloning, in a statement.

"For countries that have not yet brought in a ban, a UN convention which draws a clear distinction between reproductive cloning and therapeutic cloning will provide invaluable guidance in passing effective legislation."