US based fertility expert Dr Panos Zavos said on Saturday that he had transferred a cloned human embryo into a woman, but leading researchers expressed scepticism because he offered no scientific evidence.

Late last year Clonaid, a company founded by the Raelian movement that believes mankind was created by extraterrestrials, announced the birth of the first human clone. But scientists doubt the claim, which has never been verified.

Here is a chronology of cloning since 1997:

Feb 24, 1997 - Scientists at Scotland's Roslin Institute announce the successful reproduction of a sheep named Dolly using DNA from a single adult sheep cell. The team took a normal embryo cell from a sheep and removed its nucleus. They then took a cell from another sheep's mammary gland and used an electric current to fuse it into the emptied cell.

Mar 4, 1997 - US President Clinton issues an executive order prohibiting the use of federal funds for human cloning, citing "profound ethical issues".

June 25, 1997 - Scientists involved in the creation of Dolly reject two requests by families to use the same technique to produce exact genetic copies of relatives.

Nov 6, 1997 - The Council of Europe adopts a protocol banning human cloning.

Apr 13, 1998 - Dolly the sheep becomes a mother, giving birth to her first lamb, a female called Bonnie.

July 22, 1998 - Researchers at the University of Hawaii say they have cloned three generations of mice from adult cells.

Oct 10, 2000 - The Japanese cabinet approves a bill that imposes fines and prison terms for engaging in human cloning but stops short of banning research into human cloning altogether.

July 31, 2001 - The US House of Representatives approves legislation that will make it a federal crime to clone people to produce children or to create embryos for medical research.

Feb 2002 - Japanese researchers who cloned a dozen mice report that virtually all the animals died early.

Feb 27, 2002 - A House of Lords committee gives Britain's scientists a green light to pioneer the cloning of human embryos for research and set up the world's first embryo cell bank.

Apr 19, 2002 - Russia's parliament votes unanimously to ban human cloning and the import of cloned embryos for five years.

Nov 27, 2002 - The Vatican blasts the cloning of a human embryo by US researchers, saying it has tampered with human life.

Dec 27, 2002 - Clonaid, a company associated with the Raelian movement which believes mankind was created by aliens, announces the first human clone, a baby girl.

Jan 6, 2003 - The independent scientist and journalist brought in by Clonaid to verify its cloning denounces their claim as a possible "elaborate hoax".

Feb 14 - Six-year-old Dolly the sheep, the world's first cloned mammal, is given a lethal injection after signs of progressive lung disease are discovered.

Aug 6 - Italian scientists say they had created the world's first cloned horse, Prometea, from an adult cell taken from the horse who gave birth to her.

Dec 11 - France's lower house of parliament backed draft legislation making reproductive cloning of human cells a crime against humanity punishable by 30 years in jail and a 7.5 million euro ($9 million) fine.

Dec 16 - Scientists at Advanced Cell Technology of Worcester, Massachusetts, the only researchers to publicly show that they have cloned a human embryo, say they had successfully repeated the experiment, growing an embryo to the 16-cell stage.


Herald Feature: Cloning

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