The United Nations has blocked moves to impose a global ban on research into all forms of human cloning.
Nuclear transfer: The nucleus of a cell is transferred into an "empty" egg
The UN General Assembly's legal committee voted 80-79 in favour of an Iranian proposal to delay any decision on a ban for two years.
The move meant that members did not get the opportunity to vote on a proposal by the US and Costa Rica which would have banned human cloning.
The issue has divided the 191 member states on the committee.
BBC science correspondent Richard Black says negotiations on human cloning started over a year ago at the UN, but were postponed for a year in the face of a fundamental division between two groups of nations.
One, headed by the US and Costa Rica, wanted to ban all kinds of human cloning.
The other, led by France and Germany, wanted to ban reproductive cloning but allow therapeutic cloning - research which could lead to a new generation of medical treatments.
However, the decision to approve the Iranian call for a delay meant that neither of the rival proposals for a ban could be put to the vote.
Fifteen countries abstained in the vote on the Iranian motion, which diplomats said was intended as a compromise measure reflecting the lack of consensus.
The US deputy ambassador to the UN, James Cunningham, said 100 nations supported the US view that a total worldwide ban on human cloning was needed.
He said countries advocating a partial ban had backed the call for a delay because they feared they would lose the argument.
However, the UK's Department of Health said it was pleased that the UN had decided "not to press ahead with a ban on all forms of cloning".
The statement added that the UK Government would continue to encourage research into therapeutic cloning "which offers so many patients and their families the hope of life-saving treatments".
Correspondents say the outcome is likely to dismay mainstream scientists and ethical campaigners alike, as it leaves the door open to maverick attempts to create a human clone.