President Barack Obama has removed the ban introduced by the previous US president, George Bush, on using federal funds to support embryonic stem cell research, in an executive order issued this week.

Government support will now be available for research with many more stem cell lines than previously. These lines are developed from surplus embryos that remain after fertility treatment; the embryos would otherwise have been stored indefinitely or destroyed.

President Obama said that human cloning would never be permitted and that research would proceed under strict guidelines to be developed by the National Institutes of Health over the next four months.

The order does not provide …