The Department of Energy on Monday confirmed that it was the victim of a cyber attack in mid-January that resulted in the disclosure of personally identifiable information from employees and contractors.

In a Friday email sent to employees, the department said that no classified information was compromised in the attack.

"The Department's Cybersecurity Team, the Office of Health, Safety and Security and the Inspector General's office are working with federal law enforcement to promptly gather detailed information on the nature and scope of the incident and assess the potential impacts to DOE staff and contractors," the email said.

Still, DOE said that the personally identifiable information of "several hundred" employees and contractors "may have been affected."

"As individual affected employees are identified, they will be notified and offered assistance on steps they can take to protect themselves from potential identity theft," DOE said.

The agency said it is "leading an aggressive effort to reduce the likelihood of these events occurring again," including a boost in network monitoring and the deployment of "specialized defense tools to protect sensitive assets," though it did not elaborate.

When more details are available, DOE promised to implement a full "remediation plan."

In the meantime, it urged all employees to encrypt files and emails that include sensitive information and not to email non-government personal information on DOE network computers.

The news comes amidst a report that intelligence officials have determined that the president of the United States has the power to launch a pre-emptive strike if a major cyber attack is imminent.