Few would disagree that cloning to produce carbon copies of ourselves should be banned. It is the question of whether cloning of the type that made the news last week - the creation of early-stage embryos to be used in stem cell research - that is most contentious. Some jurisdictions - including Britain, mainland China, Singapore and South Korea - have already taken the step of banning reproductive cloning while allowing embryonic stem cell work. Hong Kong has some of the strictest rules: no reproductive cloning is allowed, while embryonic research is so limited that it is not likely ever to yield any useful results in the area of stem cells. Some countries, like Germany, have banned all cloning, while others are still debating the matter. At the United Nations, there are sharp divisions between those who would ban all cloning and those who want to allow therapeutic cloning, so the body decided in December to put off discussion for another year. In the US, there is a similar stalemate in the Senate. This lack of global agreement leaves loopholes that can be exploited for dangerous and misguided - not to mention uncontrolled - use of cloning technology that is becoming more advanced by the day. Experiments with reproductive cloning will surely continue, if not accelerate. Researchers looking at the highly credible South Korean findings liken it to a recipe book. Though the paper's authors did not take the step of implanting any of the embryos into a human womb, the possibility now exists that someone will. That is why they called for a worldwide ban on the cloning of humans for reproductive purposes. This is a step that we have advocated and still endorse. For all the peril involved in this line of research, there is promise in it as well. Stem cells are the precursors to every type of human organ and tissue, and they could one day be used to treat what are now incurable conditions, including diabetes, Parkinson's disease and Alzheimer's. The challenge will be to guide the research so that it will be safe, ethical and, most important of all, beneficial to the greatest number of people. Last week's announcement has made discussions about how to regulate cloning more urgent. It has also forced some countries, including the US, to consider whether they are losing the race to discover therapies based on stem cells because of their stalemates over policy. For Hong Kong, there is the peripheral question of whether our laws on stem cell research need to be relaxed. There have been recent suggestions that Hong Kong could become a biomedical research hub for the region. It does not have to be done now, but the laws on stem cell research may have to be revisited if we become serious about that goal. The most pressing task is finding a shared, global approach to cloning research. The questions raised are difficult ones, but they have to be addressed.