President Barack Obama said Thursday that the Justice Department will review the policy under which it obtains journalists' records in investigations of the leak of government secrets.

Obama acknowledged he is "troubled by the possibility that leaks investigations may chill the investigative journalism" that he says holds government accountable and said he has expressed his concerns to Attorney General Eric Holder. But he said his administration would continue to try to find the government employees who are responsible for leaks.

In recent weeks, the administration has acknowledged secretly seizing portions of two months of phone records from The Associated Press and reading the e-mails of Fox News reporter James Rosen in separate investigations about the publication of government secrets.

The president said the government has to strike the right balance between security and an open society. He said Holder will meet with representatives of media organizations and report back to him by July 12.

Obama re-stated his support for a media shield law that he said would "guard against government overreach." Such a law would require a federal judge to sign off before investigators could have a look at the records of journalists.

"Journalists should not be at legal risk for doing their jobs. Our focus must be on those who break the law," Obama said.

The seizure of the AP phone records is part of an investigation into who leaked information to AP reporters for a May 7, 2012, story that disclosed details of a foiled plot in Yemen to bomb a U.S.-bound airliner, around the anniversary of the May 2, 2011, killing of Osama bin Laden.

Rosen's emails were seized, with a judge's approval, as part of the prosecution of Stephen Kim, a State Department adviser who is accused of leaking secret information about North Korea.

AP President and CEO Gary Pruitt has called the Justice Department's actions in the AP case "unconstitutional" and he has protested what he termed a massive and unprecedented intrusion into how news organizations go about gathering the news.

Pruitt said the seizure already has had a chilling effect on newsgathering.

Following the president's speech, AP spokeswoman Erin Madigan said, "We recognize that the guidelines need improvement and support a review under the right conditions."

The Justice Department is guided by policy that first was written 40 years ago after the excesses of the Watergate era. Investigators are not supposed to consider a subpoena for journalists' phone records unless "all reasonable attempts" have been made to get the same information from other sources, the rules say.

News organizations are supposed to get advance warning so that they can fight a subpoena in court, except if the notification could compromise the investigation. AP received no advance warning.

The attorney general also must personally approve the subpoena before it is issued. In the AP case, Holder had been interviewed by the FBI as part of its effort to find out who had improperly disclosed the information, so he stepped aside to avoid a conflict of interest and left the decision to Deputy Attorney General James Cole.

Obama offered no apologies for his administration's aggressive pursuit of leakers. The six prosecutions since he took office in 2009 is more than in all other presidencies combined.

"As commander in chief, I believe we must keep information secret that protects our operations and our people in the field. To do so, we must enforce consequences for those who break the law and breach their commitment to protect classified information," he said.