WASHINGTON  The Obama administration has inserted language into the federal jobs Web site explicitly banning employment discrimination based on gender identity.

The protection is expected to apply to the small transgender population  people who identify their gender differently from the information on their birth certificates  and it merely formalizes what had been increasingly unchallenged government practice over several years.

But civil liberties and gender rights groups welcomed it on Tuesday as the clearest statement yet by the Obama administration that such discrimination in the federal workplace would not be accepted.

Mara Keisling, executive director of the National Center for Transgender Equality, said, “The largest employer in the country is doing what all the other large employers in the country are doing, so that’s really great news.”