A leap forward or a step too far? The new debate over embryo research

British scientists are limited to research on embryos under 14 days old - until recently no one was able keep an embryo alive that long. But now an ethical struggle looms

Later this week some of the world's leading scientists will gather at University College London to debate a simple but highly controversial notion: that it is time to scrap the 14-day limit on embryo research.

Thanks to recent scientific breakthroughs, researchers have reached a point where they can begin to think of experimenting on embryos up to 28 days in age. The benefits for medical science would be considerable.