WASHINGTON — Attorney General Eric H. Holder Jr. on Friday assigned two United States attorneys to lead separate criminal investigations into recent disclosures to the news media of national security secrets, saying they were authorized to “follow all appropriate investigative leads within the executive and legislative branches of government.”

Their appointment followed calls in Congress this week for a crackdown on leaks after a recent series of disclosures on topics ranging from drone strikes to a computer virus attack against Iran’s nuclear program. Several of the revelations were published by The New York Times.
“The unauthorized disclosure of classified information can compromise the security of this country and all Americans, and it will not be tolerated,” Mr. Holder said in a statement. “The Justice Department takes seriously cases in which government employees and contractors entrusted with classified information are suspected of willfully disclosing such classified information to those not entitled to it, and we will do so in these cases as well.”
Several members of Congress from both parties this week expressed alarm about recent leaks, and some Republicans had called for the appointment of a special prosecutor with greater independence from day-to-day supervision by the Obama administration to investigate.
But Mr. Holder instead assigned two prosecutors — Ronald C. Machen, the United States attorney for the District of Columbia, and Rod J. Rosenstein, his counterpart in Maryland — to take over direction of existing investigations by the Federal Bureau of Investigation, elevating the stature of the cases but not giving them any special powers.
Earlier on Friday, President Obama declared that the White House had not been behind a recent series of leaks and vowed to prosecute the people responsible for disclosing classified information if they could be identified.
“Since I’ve been in office, my attitude has been zero tolerance for these kinds of leaks and speculation,” Mr. Obama said at a news conference. “Now we have mechanisms in place where, if we can root out folks who have leaked, they will suffer consequences. In some case, it’s criminal. These are criminal acts when they release information like this. And we will conduct thorough investigations, as we have in the past.”
The Obama administration has already compiled an aggressive record of prosecuting people accused of leaking national security secrets. It has brought six such cases, compared with three under all previous presidents combined.
The recent spate of disclosures included the revelation that a plot by the Yemen branch of Al Qaeda to bomb an airliner had been foiled because of penetration by a double agent, details about the joint American-Israeli computer virus called Stuxnet that sabotaged Iran’s nuclear centrifuges, and an account of Mr. Obama’s role in approving a “kill list” of terrorism suspects for drone strikes.
They include recent reports published by The New York Times, The Associated Press, Newsweek and other news media outlets, some of which were derived from recently published books by reporters for The Times and Newsweek. They followed previous disclosures about the operation that located and killed Osama bin Laden, both in the aftermath of the raid and then again around its anniversary this spring.
The Justice Department did not say which leaks in particular were now under investigation, apparently because doing so would implicitly confirm that certain reports contained accurate classified information.
Some Republicans have accused the White House of risking national security for political gain in an election year by deliberately disclosing secret information that makes Mr. Obama look tough — even as it prosecutes lower-level current and former officials for other leaks that did not confer any political advantage.
“It is difficult to escape the conclusion that these recent leaks of highly classified information, all of which have the effect of making the president look strong and decisive on national security in the middle of his re-election campaign, have a deeper political motivation,” said Senator John McCain of Arizona, the ranking Republican on the Senate Armed Services Committee and Mr. Obama’s 2008 presidential campaign opponent, this week.
But Mr. Obama called such accusations wrong.
“The notion that my White House would purposefully release classified national security information is offensive,” he said, adding: “But as I think has been indicated from these articles, whether or not the information they’ve received is true, the writers of these articles have all stated unequivocally that they didn’t come from this White House, and that’s not how we operate.”
After Mr. Obama’s remarks, Mr. McCain reiterated his call for a special counsel, noting that several passages of the recent articles and books cited senior administration sources.
While still accountable to the attorney general, a special counsel has greater day-to-day independence and can be appointed to look into high-level executive branch wrongdoing. During the Bush administration, for example, Patrick J. Fitzgerald, the United States attorney in Chicago, was appointed special counsel to investigate the disclosure of the identity of Valerie Plame Wilson, a Central Intelligence Agency operative, and eventually charged Vice President Dick Cheney’s top aide, I. Lewis Libby, with perjury.
While the two prosecutors are not special counsels, Mr. Holder called them “highly respected and experienced” and said that he had “every confidence in their abilities to doggedly follow the facts and the evidence in the pursuit of justice wherever it leads.”
“In carrying out their assignments, U.S. Attorneys Machen and Rosenstein are fully authorized to prosecute criminal violations discovered as a result of their investigations and matters related to those violations, consult with members of the intelligence community and follow all appropriate investigative leads within the executive and legislative branches of government,” he said.
In comments to several news outlets earlier this week, Dean Baquet, managing editor of The Times, said the newspaper’s reporters had come by the information through “tons and tons of reporting” over the course of months, not handouts. He also said the newspaper had told officials about its findings ahead of their publication and withheld some technical details about the Stuxnet operation at their request.
While several of the articles quoted administration officials in the accounts of decisions and meetings, they did not say where the underlying information came from. On Friday, Danielle Rhoades Ha, a spokeswoman for The Times, said the newspaper had nothing further to say.
“We do not discuss sourcing in articles,” she said.