WASHINGTON - Federal investigators secretly seized two months of phone records for reporters and editors of The Associated Press in what the news organization said Monday was a "serious interference with AP's constitutional rights to gather and report the news."

The AP said that the Justice Department informed it on Friday that law enforcement officials had obtained the records for more than 20 telephone lines of its offices and journalists, including their home phones and cellphones. It said the records were seized without notice sometime this year.

The organization was not told the reason for the seizure. But the timing and the specific journalistic targets of the seizure strongly suggested they are related to a continuing government investigation into the leaking of information in May 2012 about the CIA's disruption of a Yemen-based terrorist plot to bomb an airliner.

The disclosures began with an AP article on May 7, 2012, breaking the news of the foiled plot; the organization had held off publishing it for several days at the Obama administration's request because the intelligence operations were still unfolding.

In an angry letter to Attorney General Eric H. Holder Jr. on Monday, Gary Pruitt, the president and chief executive of the AP, called the seizure a "massive and unprecedented intrusion" into its newsgathering activities.

"There can be no possible justification for such an overbroad collection of the telephone communications of The Associated Press and its reporters," he wrote. "These records potentially reveal communications with confidential sources across all of the newsgathering activities undertaken by the AP during a two-month period, provide a road map to AP's newsgathering operations, and disclose information about AP's activities and operations that the government has no conceivable right to know."

The development represents the latest collision of news organizations and federal investigators over government efforts to prevent the disclosure of national security information, and it comes against a backdrop of an aggressive policy by the Obama administration to rein in leaks. Under President Barack Obama, six current and former government officials have been indicted in leak-related cases so far, twice the number brought under all previous administrations combined.

Justice Department regulations call for subpoenas for journalists' phone records to be undertaken as a last resort and narrowly focused, subject to the attorney general's personal signoff. Under normal circumstances, the regulations call for notice and negotiations, giving the news organization a chance to challenge the subpoena in court.

The Justice Department referred questions about the subpoena to a spokesman for Ronald C. Machen Jr., the U.S. attorney for the District of Columbia, who was assigned by Holder in June to lead one of two major leak investigations. Those inquiries came amid a congressional uproar over several disclosures of national security information in the media.

"We must notify the media organization in advance unless doing so would pose a substantial threat to the integrity of the investigation," Machen's spokesman, William Miller, said.

"Because we value the freedom of the press," Miller added, "we are always careful and deliberative in seeking to strike the right balance between the public interest in the free flow of information and the public interest in the fair and effective administration of our criminal laws."

But First Amendment experts and free press advocates portrayed the move as shocking in its breadth.

The Newspaper Association of America issued a statement saying: "Today we learned of the Justice Depart-ment'sunprecedented wholesale seizure of confidential telephone records from the Associated Press. These actions shock the American conscience and violate the critical freedom of the press protected by the U.S. Constitution and the Bill of Rights."

A spokeswoman for Dow Jones, which owns The Wall Street Journal, said the company was concerned about the "broader implications" of the action.

Jay Carney, a White House spokesman, said the White House was not involved in the subpoena.

"Other than press reports, we have no knowledge of any attempt by the Justice Department to seek phone records of the AP," he said. "We are not involved in decisions made in connection with criminal investigations, as those matters are handled independently by the Justice Department."

The Justice Department did not respond to a question about whether a similar step was taken in another major government leak investigation, believed to be focused on a New York Times reporter, David E. Sanger, and his disclosures in articles and in a book about a joint U.S.-Israeli effort to sabotage Iranian nuclear centrifuges with the so-called Stuxnet virus.

David McCraw, a lawyer for The New York Times, said, "We've had no contact from the government of any sort."

Holder announced the two special leak investigations in June amid calls in Congress for a crackdown on leaks after a spate of disclosures about the bomb plot, the alleged Iranian sabotage, Obama's procedures for putting terrorism suspects on a "kill list," and the raid that killed Osama bin Laden.

The revelations had been published by The New York Times, AP, and in several books; separately, administration critics contended that filmmakers working on a movie about the bin Laden raid, "Zero Dark Thirty," had been given special access by the CIA.

Republicans accused the administration of deliberately leaking classified information, jeopardizing national security in an effort to make Obama look tough in an election year - a charge the White House rejected. But some Democrats, too, said the leaking of sensitive information had gotten out of control, including Sen. Dianne Feinstein of California, the chairwoman of the Senate Intelligence Committee.

Holder's move at the time was sharply criticized by Republicans as not going far enough. They wanted him to appoint an outside special counsel, and a Senate resolution calling for a special counsel was co-sponsored by 29 Republican senators.

On Monday, however, after the AP disclosed the seizure of the records, some Republican leaders criticized the administration as going too far. Michael Steel, a spokesman for House Speaker John A. Boehner, said: "The First Amendment is first for a reason.If the Obama administration is going after reporters' phone records, they better have a damned good explanation."

And Douglas Heye, a spokesman for Rep. Eric Cantor, R-Va. and the House majority leader, linked the revelation to a brewing controversy over the targeting of Tea Party groups for greater scrutiny by the Internal Revenue Service.

"Whether it is secretly targeting patriotic Americans participating in the electoral progress or reporters exercising their First Amendment rights, these new revelations suggest a pattern of intimidation by the Obama administration," Heye said.

The AP said Monday that it first learned of the seizure of the records last Friday afternoon whenits general counsel, Laura Malone, received a letter from Machen, the U.S. attorney.

The AP's letter to Holder said the seizure included "all such records for, among other phone lines, an AP general phone number in New York City as well as AP bureaus in New York City, Washington, D.C., Hartford, Conn., and at the House of Representatives."

In an article it wrote about the seizure, the AP said that "more than 100 journalists work in the offices whose phone records were targeted." The Associated Press is a nonprofit global news cooperative owned by its U.S. newspaper and broadcast members.