The National Archives and Records Administration last month warned 150,000 more people who interacted with the Clinton administration that their personal information may be at risk after a hard drive was lost.

The December letters were the second batch sent in connection with the March data loss. Previously, NARA mailed more than 26,000 letters to potential identity theft victims, according to the agency's Jan. 4 statement. Data on the drive included the names and Social Security numbers of White House employees, job applicants and White House visitors.

In the letters, NARA offers affected individuals one year of free credit monitoring, identify theft insurance and fraud resolution assistance through the credit monitoring firm Experian.

In May, NARA offered a $50,000 reward for the return of the external hard drive, which was last seen March 24 in a processing room at the Archives' College Park, Md., office. The agency's inspector general is investigating the data loss, which did not involve any original administration records. A July posting on NARA's Web site says it is unclear whether the hard drive's disappearance was theft or other criminal activity.

Those affected should call 877-281-0771 or 301-837-3769, or e-mail breach_response@nara.gov.