The federal agency that oversees the nation's power grid was a prime target of nine Iranian hackers whom the Justice Department is indicting for “malicious” cyber activity, the agency revealed Friday morning.

Justice Department lawyers pointed out during a press conference that the Federal Energy Regulatory Commission “has the details of some of this country’s most sensitive infrastructure," said U.S. Attorney Geoffrey Berman. “That is the agency that regulates the interstate transmission of electricity, natural gas and oil.”

A FERC spokesman said the commission "has and will continue to work cooperatively and diligently with other federal authorities on this matter. The hacks had resulted in "a small number of e-mail accounts" being "inappropriately accessed," the spokesman said.

Since then, the commission "has taken and will continue to develop corrective action to ensure that appropriate controls are operating effectively," he said.

The Justice Department said FERC was among federal, state and United Nations agencies targeted, including the Department of Labor, Hawaii, Indiana, the United Nations, and the United Nations Children’s Fund.

“The defendants were each leaders, contractors, associates, hackers-for-hire or affiliates of the Mabna Institute, an Iran-based company that, since at least 2013, conducted a coordinated campaign of cyber intrusions into computer systems belonging to 144 U.S. universities, 176 universities across 21 foreign countries, 47 domestic and foreign private sector companies,” as well as the agencies mentioned, Justice said.

The Justice Department said the cyber assailants were acting at the behest of the Iranian regime's Islamic Revolutionary Guard. Berman said the Iranian cyber campaign represents "one of the largest state-sponsored hacking campaigns ever prosecuted by the Department of Justice."

The "massive and brazen cyber-assault on the computer systems" of universities and governmental organizations "was conducted on behalf of Iran’s Islamic Revolutionary Guard," Berman said. "The hackers targeted innovations and intellectual property from our country’s greatest minds. These defendants are now fugitives from American justice, no longer free to travel outside Iran without risk of arrest. The only way they will see the outside world is through their computer screens, but stripped of their greatest asset — anonymity.”