The National Security Agency for the first time has admitted that some of their employees have spied on their girlfriends, boyfriends and spouses, listening to phone calls and checking emails without cause, known internally as LOVEINT, or love intelligence. NBC's Michael Isikoff reports.

National Security Agency employees improperly eavesdropped on the phone calls of girlfriends, boyfriends, husbands, wives and spouses and engaged in other "intentional" abuses of their authority on 12 occasions since 2003, according to a newly released letter by the agency's inspector general.

The agency also has two open investigations into alleged misuse of its eavesdropping authorities and is reviewing a third one for possible investigation, according to a letter by NSA inspector general Dr. George Ellard.

Ellard's letter – in response to an inquiry by GOP Sen. Charles Grassley – was prompted by media reports that NSA employees at times have been caught in what is informally known as "loveint" – collecting intelligence on love interests. But until now, the specific examples and the frequency of such cases have never been disclosed by the NSA.

In one case revealed by Ellard, an NSA employee for five years snooped on the phone calls of nine female foreign nationals "without a valid foreign intelligence purposes." In another, 2011 instance, an NSA employee admitted it was "her practice" to eavesdrop on foreign phone numbers "she obtained in social settings" in order to ensure she was not talking to “shady characters.'' Both employees resigned before any disciplinary action could be taken.

"What's clear about the instances of abuse is that these have nothing to do with terrorism," said Anthony Romero, executive director of the American Civil Liberties Union. "This is about individuals prying into the private lives of the people closest to them. It's an abuse of government data that should not be in the government's hands."

Among other examples cited in Ellard's letter:

In 2011, an NSA employee acknowledged that "out of curiosity" he had tried to listen in on the phone calls of his girlfriend, a foreign national. The agency's system blocked him from doing so, but the employee did retrieve "metadata"-- records of time, date and duration of the girlfriend's phone calls. The subject's actions were referred to the Justice Department, which declined prosecution.

In 2005, the NSA discovered that another NSA employee eavesdropped for a month "without an authorized purpose" on the phone calls of his foreign national girlfriend. The employee was trying to determine if she was "involved" with any foreign officials or engaged in other activities that "might get him in trouble." The employee retired before the investigation into his activities was finished.

In 2004, a NSA employee retrieved data on a foreign telephone number she had discovered on her husband's cell phone. The case was referred to the Justice Department for prosecution, but the employee resigned before any NSA discipline could be imposed. The letter does not address whether there was a prosecution effort.

Jason Reed / REUTERS Gen. Keith Alexander, director of the National Security Agency, testifies Thursday at a Senate Intelligence Committee hearing in Washington. Alexander said that according to the agency's inspector general, "there have been only 12 substantiated cases of willful violations over 10 years, essentially one per year."

In testimony before the Senate Intelligence Committee on Thursday, NSA Director Gen. Keith Alexander said of allegations of agency abuses: "The press claims evidence of thousands of privacy violations. This is false and misleading. According to NSA's independent Inspector General there have been only 12 substantiated cases of willful violations over 10 years, essentially one per year. "

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