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The Energy Department has been hit by a major cyber-attack, which resulted in the personal information of several hundred employees being compromised and could have been aimed at obtaining other sensitive information, The Washington Free Beacon reports.

FBI agents are investigating the attacks, which happened two weeks ago, at the Washington-based headquarters. Fourteen computer servers and 20 workstations reportedly were penetrated during the attack.

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The Energy Department is in the process of notifying employees whose information was stolen. While no classified information was compromised, the Free Beacon reports there are indications the hackers could have been seeking access to such data. Chinese hackers may be suspects, as the department is a known target of Beijing -- according to the Free Beacon, the sophistication of the attack indicates the involvement of a foreign government.

The department includes the National Nuclear Security Administration, which maintains nuclear weapons.

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"It's a continuing story of negligence," former Energy Department security official Ed McCallum told the Free Beacon, explaining that the department continues to have security problems despite controlling some of the most "sophisticated military and intelligence technology the country owns."

He said China, as well as Iran, have been after Energy Department secrets. Several groups and agencies have warned about stepped-up cyber activities out of China.

"China continues to develop its capabilities in the cyber arena," the U.S. China Economic and Security Review Commission said in a November 2012 report to Congress. "U.S. industry and a range of government and military targets face repeated exploitation attempts by Chinese hackers as do international organizations and nongovernmental groups including Chinese dissident groups, activists, religious organizations, rights groups, and media institutions."

Officials tell the Beacon they're working to plug security holes in the system and are developing ways to prevent a similar cyber attack in the future.

Confirmation of the attack comes only days after The New York Times and The Wall Street Journal announced that Chinese hackers had infiltrated its computers and stolen passwords for its employees. In a written statement, News Corporation, parent company of FoxNews.com, described the attack as an "ongoing issue." China's Ministry of National Defense has denied accusations they were behind the cyber attacks.

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The Washington Free Beacon's Bill Gertz contributed to this report.