British Prime Minister Gordon Brown called today for members of parliament to support research using embryonic stem cells, including human-animal hybrid embryos, ahead of an important vote in parliament.
The issue of embryonic cell research has divided Brown's government - some members of his cabinet oppose it on religious grounds - at a time when he is faring poorly in opinion polls.
Brown has allowed a "free vote" in parliament tomorrow on some of the most controversial parts of a human reproduction bill, allowing members of his Labour Party to oppose them if they choose without being required to resign from the cabinet.
But in an article in the Observer newspaper, the prime minister said the research could "save and transform millions of lives" by providing important therapies to fight disease.
"That is why we have - patiently and with full regard for religious concerns - sought to introduce clear laws which permit the use of stem cells within a clear, managed, legal framework subject to the strictest supervision," Brown wrote.
British scientists have been pioneers in research on using "stem cells" - undifferentiated cells that can turn into many types of tissue - to cure disease.
Among the controversial aspects of the research are the so-called hybrid embryos, which involve putting human DNA into cells derived from animals to produce stem cells.
"Around the world, researchers now face a severe shortage of embryonic stem cells," Brown wrote.
"They argue that the safest way to maintain progress is to make use of animal eggs from which the animal genetic material is almost entirely removed, then a human cell nucleus added, to make them compatible for research on human diseases."
Tomorrow's debate is expected also to see heated discussion of abortion, with some members of parliament seeking to amend the bill to reduce the 24-week period in which women are normally permitted to terminate pregnancies.