WASHINGTON - U.S. President Barack Obama directed federal agencies on Thursday to enact new rules governing federally funded research on human embryonic stem cells.

The rules, issued earlier this year by the National Institutes of Health, loosened some ethical requirements that scientists said could have cost them a decade of work.

I hereby direct the heads of executive departments and agencies that support and conduct stem cell research to adopt these guidelines, to the fullest extent practicable in light of legal authorities and obligations, Obama said in a statement.

In March, Obama lifted restrictions on human embryonic stem cell research that had been put in place by his predecessor as president, George W. Bush, and asked the NIH to draw up new guidelines.