The Obama administration’s hostility toward media and efforts to crack down on whistleblowers and leakers has created "a tremendous chilling effect" on substantive reporting, the Committee to Protect Journalists and veteran reporters said Thursday.

The CPJ issued last week a scathing report, written by former Washington Post executive editor Leonard Downie, Jr., on the effects of the Obama administration’s efforts to control press coverage, burnish its image, and thwart unauthorized leaks.

Downie joined a panel at the New America Foundation that included Joel Simon, executive director of the CPJ, and Rajiv Chandrasekaran, senior correspondent and associate editor at the Washington Post, to discuss the report on Thursday.

"The Obama administration’s aggressive war on leaks, and its determined efforts to control information that the news media needs to hold the government accountable for its actions, are without equal since the Nixon administration and in direct conflict with President Obama's often-stated goal of making his administration the most transparent in American history," Downie said.

"Parenthetically, I'm old enough that I was one of the editors on the Watergate story, so I make that comparison with knowledge," he continued.

The report outlines how the Obama White House has fallen far short of the president’s promises to usher in "the most transparent administration in history."

Six government employees and two contractors have been prosecuted under the Espionage Act of 1917 for leaking information to the press since Obama took office—more than all previous administrations combined.

The Justice Department secretly subpoenaed the phone records and emails of journalists suspected of consorting with leakers.

The Obama administration also created an "Insider Threat Program" to ferret out internal information leaks.

As previously reported by the Washington Free Beacon, the government-wide failures with the Freedom of Information Act have continued, and in some cases accelerated, under President Barack Obama.

The Obama White House also began an unprecedented effort to produce its own administration-generated news and information while locking out reporters from more events than ever, the report said.

"Putting them all together suggests that this is not a haphazard response to events," Simon said at Thursday’s event. "There is a systematic effort to marginalize and undermine the work of the press."

Downie interviewed dozens of reporters who told him that the Obama White House was fundamentally different from other administrations.

The New York Times’ David Sanger told Downie the Obama administration is the "most closed, control-freak administration" he has ever covered.

"He’s the least transparent of the seven presidents I’ve covered in terms of how he does his daily business," ABC News White House correspondent Ann Compton told Downie.

Other reporters described the Obama administration’s "across the board hostility" to press, overblown reactions to stories perceived as negative, and an overwhelming need to control its message.

But the biggest concern for Downie and the CPJ is the effect of leak prosecutions on national security reporting. Washington reporters told Downie the prosecution of leakers has had a large chilling effect on their reporting. Sources are afraid to talk.

"I worry now about calling somebody because the contact can be found out through a check of phone records or e-mails," veteran national security journalist R. Jeffrey Smith of the Center for Public Integrity, told Downie. "It leaves a digital trail that makes it easier for the government to monitor those contacts," he said.

Chandrasekaran said at Thursday’s event many of his colleagues now avoid email and phone conversations with sensitive sources. Some use computers without Internet connections—crude imitations of the Sensitive Compartmented Information Facilities (SCIFs) used by the intelligence community.

This week, in response to increasing media fear of government snooping, the Freedom of the Press Foundation launched SecureDrop, an encrypted program for reporters and sources to exchange information.

The White House pushed back against the report last week, highlighting some of the transparency reforms it has accomplished.

"As part of the president’s unparalleled commitment to reforming Washington, this administration is the first ever to release White House visitor records," White House spokesman Eric Schultz told Politico. "Over the past four years, federal agencies have gone to great efforts to make government more transparent and more accessible than ever, to provide people with information that they can use in their daily lives. Just this past year, the government processed more [Freedom of Information Act] requests, decreased the backlog, improved average processing times, and disclosed more information proactively."