Monstrous to some, but representing a ray of hope in the fight against debilitating diseases to others, stem-cell research has been steeped in controversy for over a decade.

While scientists, doctors, patient groups and medical charities welcome the ground-breaking advances it could bring, the Roman Catholic Church and several other faiths are vehemently opposed to stem-cell research on the grounds that it compromises the sanctity of human life. Central to the religious objectors' argument is that using stem cells amounts to deriving benefit from the destruction of human embryos - fertilized eggs in the early stages of development - and is therefore tantamount to murder, and certainly little better than abortion.

Yet supporters of the revolutionary research techniques are thrilled that stem cells taken from embryos can be made to grow into any cell in the human body, providing an extraordinary resource in the fight against Alzheimer’s, Parkinson’s, Motor Neurone Disease, diabetes and other conditions.

Here in the UK, The Human Fertilisation and Embryology Bill, which will permit the creation of human-animal hybrid embryos, is going through Parliament. After warnings that some Catholic Labour MPs and cabinet ministers were ready to rebel, the Prime Minister has granted Labour MPs a free vote on the most controversial elements, allowing them to follow their consciences.

In March this year Cardinal Keith O’Brien used his Easter Sunday sermon to launch a scathing attack on the Bill, describing the proposals as “grotesque” and “deathly”. “One might say that in our country we are about to have a public Government endorsement of experiments of Frankenstein proportion,” he told worshippers in Edinburgh, “without many people really being aware of what is going on.”

Over in the pro-research camp, medical research charities have written to MPs urging them to support the Bill. Dr Chris Kingswood, Head of Research at the Tuberous Sclerosis Association believes hybrid embryo research is a powerful tool for discovering the basic problems in genetic and other diseases and accelerating the chance of finding treatments or cures. “Carried out in a proper legal framework its potential benefits far outweigh any of the dangers,” he says.

He explains the significance of human-animal hybrid embryos, saying: “The advantage of using animal eggs is that they are readily available. Doing this research with human eggs is difficult because they are so scarce.” However he acknowledges that a major concern is the creation of a half animal/half human being, or ‘chimera’, through scientific research. “There needs to be an understanding that this would not be possible, and would be specifically forbidden by the new law,” he reassures.

The legal definition of when an embryo is considered alive is at 24 weeks; when all the organs have formed and it contains millions and millions of cells. The new legislation that is proposed is that cytoplasmic hybrid embryos should not be allowed to go beyond 14 days, when they will still be just a collection of cells.

Islam, which does not have a centralised authority akin to the Vatican in Roman Catholicism, has no stated opinion on the issue of stem-cell research and most Muslim countries are yet to introduce laws on embryonic stem-cell research and human cloning. Reportedly, some Muslims are in favour of research, arguing that the embryo does not have a soul until the later stages of its development. Others agree with the Catholic line of reasoning however, that to destroy embryos at any stage to harvest stem cells is immoral. Similarly Buddhists support the principle of non-harming, and therefore many have grave reservations about any scientific procedure that destroys life, whether human or animal.

Some religions actively support the movement. For instance Episcopalians in North America offered praise for the passage of US legislation in 2005 expanding research of donated stem cells derived from human embryos after in vitro fertilization. A statement from Episcopal Church leaders at the time said: “The Episcopal Church celebrates medical research as it expands our knowledge of God’s creation and empowers us to bring potential healing to those who suffer from disease or disability.”

US, UK and European legislation is treading a careful line, and western opponents to the latest stem cell research procedures should bear in mind that if a strict legal framework is agreed, it will at least provide an ethical benchmark for other countries and cultures to consider. Certainly stopping stem-cell research here will not prevent it happening elsewhere in the world.