The chief of the U.S. federal hiring office resigned on Friday after massive computer hacks at the agency that put the personal data of more than 22 million Americans at risk, including people seeking sensitive security clearances.

The White House said Katherine Archuleta stepped down as head of the Office of Personnel Management and that OPM was enhancing cyber-security measures, such as limiting the number of "privileged users" of computer data.

Archuleta, facing a chorus of demands from Congress for her ouster, said in a statement she had told President Barack Obama it was "best for me to step aside and allow new leadership to step in."