Updated

Personal information for 250,000 Clinton administration staff and White House visitors sent to the National Archives was compromised after a computer hard drive containing confidential material disappeared nearly a year ago, RollCall.com reported Wednesday.

The National Archives and Record Administration sent letters to former White House staff members and visitors during the Clinton era, informing them of the data breach and warning that highly sensitive information, like Social Security numbers, has been put in jeopardy, according to the newspaper.

"NARA is attempting to inform all individuals whose personally identifiable information was contained on the missing hard drive," acting archivist Adrienne Thomas reportedly wrote in the letter.

The hard drive was part of a storage collection containing contents of computers of former Clinton administration employees, including one of former Vice President Al Gore's daughters, whose Social Security number was on the drive, Roll Call reported.

The hard drive was reported missing in March 2009, according to the newspaper.

Click here to read more on this story from RollCall.com (subscription required).