The U.S. Department of Veterans Affairs (VA) is investigating a missing hard drive containing the personal records of 48,000 military veterans, the agency said.

The external hard drive contained about 20,000 personal records that were not encrypted, according to information from U.S. Representative Spencer Bachus, an Alabama Republican. A VA employee reported the hard drive missing from an agency Birmingham, Alabama, facility on Jan. 22, according to a VA press release.

The VA and the U.S. Federal Bureau of Investigation are investigating the missing hard drive, the VA said in its Friday press release. The VA's Office of Information and Technology is conducting a separate investigation, Jim Nicholson, VA's secretary, said in a statement.

"We intend to get to the bottom of this, and we will take aggressive steps to protect and assist anyone whose information may have been involved," Nicholson added.

In May, the VA reported a laptop and hard drive containing the personal records of 26.5 million military veterans and their families had been stolen from an employee's home. Police later recovered the hardware, and the VA said computer forensics tests indicated thieves had not accessed the data, but the theft set off criticism from several members of Congress about the VA's cybersecurity practices.

The hard drive in Alabama was used to back up information contained on an employee’s office computer, and may have contained data from research projects the employee was involved in, as well as personal information, the VA said.

The VA Office of Inspector General has seized the employee’s computer and is analyzing its contents, the VA said. The VA is prepared to notify affected people and provide free credit monitoring, the agency said.

The VA will continue to aim to be a leader in protecting personal information, Nicholson said in his statement.

In August, the VA also reported that a desktop computer containing the personal information of 38,000 veterans was missing from the office of Unisys Corp., the subcontractor assisting at the agency's medical centers in Pittsburgh and Philadelphia.

The lost VA hardware prompted a congressional review of other U.S. government agencies, and agencies reported thousands of laptops missing in the last five years.