'POINTED QUESTIONS'

The AP is assessing options for legal action in response to the government's actions, said Schulz, the attorney.

The Justice Department has issued rules that apply to subpoenas seeking phone records for news organizations. The subpoenas must be approved by the attorney general, drawn as narrowly as possible and used only when other attempts to get the information have failed.

The department is also required to notify the organization and seek to negotiate an agreement before issuing those subpoenas, as long as "such negotiations would not pose a substantial threat to the investigation at issue. Pruitt said that the AP was not notified in advance.

The AP may have little recourse to fight the subpoenas in court, since they were served not on the news organization but, presumably, on phone companies, legal experts said.

David Anderson, a law professor at the University of Texas at Austin and an expert in media law, said there is no prohibition against seeking phone records to pursue potential leaks.

"There's nothing unusual about that, except that it's a news organization," said Anderson, who noted that the subpoenas could have a "terrible effect" by discouraging sources from talking to reporters.

Laura Murphy, director of the Washington legislative office of the American Civil Liberties Union, said that the incident was part of a pattern by the Obama administration in going after whistleblowers and leaked information.

"The Obama administration has been one of the most aggressive administrations in history when it comes to going after whistleblowers, and we find their conduct highly disturbing, and this is part of a pattern," she said in a phone interview.

Among at least a half-dozen prosecutions by the Obama White House - more than all other previous presidents combined, according to tallies by multiple news organizations - the Justice Department charged former National Security Agency official Thomas Drake under the Espionage Act with mishandling classified information.

On the eve of his trial, the government dropped the charges in exchange for Drake pleading guilty to a misdemeanor charge.

Republican Representative Robert Goodlatte, chairman of the House Judiciary Committee, said in a statement that the panel intends to ask Holder "pointed questions" about the issue when he testifies on Wednesday at a previously scheduled general oversight hearing.

House Oversight and Government Reform Committee Chairman Darrell Issa, a Republican who has been criticizing the Obama administration on several fronts, including over last year's attacks on the US mission in Benghazi, Libya, faulted the administration for the Justice Department action.

"Coming within a week of revelations that the White House lied to the American people about the Benghazi attacks and the IRS targeted conservative Americans for their political beliefs, Americans should take notice that top Obama Administration officials increasingly see themselves as above the law and emboldened by the belief that they don't have to answer to anyone," Issa said in a statement.

Senate Judiciary Committee Chairman Patrick Leahy, a Democrat from Vermont, said he was "very troubled" by the allegations and wants to hear the government's explanation.

"The burden is always on the government when they go after private information - especially information regarding the press or its confidential sources. I want to know more about this case, but on the face of it, I am concerned that the government may not have met that burden," he said in a statement.