The Associated Press is reporting that the US Department of Justice secretly spied on phone lines used by up to 100 of its reporters in a sweeping surveillance campaign, obtaining personal telephone numbers and details about sources and stories. The Justice Department reportedly obtained subpoenas to access phone records for 20 separate phone lines used by AP staffers for the period of April to May 2012.

The DOJ notified the AP of this surveillance operation in a letter the AP received Friday, but did not specify a reason as to why it was surveilling the reporters. The AP speculates that the move had something to do with the US government's previously stated investigation into leaked information about a foiled Yemeni terror plot that appeared in a story published by the AP on May 7, 2012. Still, the AP's CEO is blasting the move as an invasion of privacy and a chilling effect on the First Amendment right to the freedom of the press. As AP CEO Gary Pruitt wrote in a letter to the Justice Department on Monday:

"There can be no possible justification for such an overbroad collection of the telephone communications of The Associated Press and its reporters. 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," Pruitt said.

A spokesperson for US attorney Ronald Machen of the District of Columbia, who issued the subpoenas for the AP's phone records, told the AP that the Justice Department followed all laws and applicable procedures in this case. The spokesperson declined to comment further, citing an ongoing criminal investigation.

Update: The ACLU has also come out vehemently against the Justice Department's subpoena of AP phone records, putting out several statements calling the move an "unacceptable abuse of power," and calling upon Attorney General Eric Holder to "explain the Justice Department's actions to the public so that we can make sure this kind of press intimidation does not happen again."

Update: An AP spokesperson told The Verge the organization has no intention to publish the letter it received from the Justice Department on the subpoena of AP phone logs. "We're not planning to do that, that's all I can say," said Erin Madigan White, AP manager of media relations.

Update: The White House denies having had any knowledge of the DOJ's seizure of AP phone records. On Monday, White House Press Secretary Jay Carney made the following statement, posted by The Daily Caller:

"Other than press reports, we have no knowledge of any attempt by the Justice Department to seek phone records of The AP. We are not involved in decisions made in connection with criminal investigations, as those matters are handled independently by the Justice Department. Any questions about an ongoing criminal investigation should be directed to the Department of Justice.”

Update: The AP has released CEO Gary Pruitt's letter to the DOJ in its entirety. Many of the claims made in the letter have already been described in detail, but Pruitt points specifically to a violation of regulation 28 C.F.R. §50.10, which requires that any subpoena "be as narrowly drawn as possible" Pruitt calls for the DOJ to "immediately return to the AP the telephone toll records that the Department subpoenaed and destroy all copies. At a minimum, we request that you take steps to segregate these records and prohibit any reference to them pending further discussion."