White House spokesman Jay Carney said at the daily briefing that he would not comment on the development of a whistle-blower who admitted he was behind the recent leaks of classified surveillance programs.

　　"I will say at the outset that there is obviously an investigation underway into this matter," Carney said, "And for that reason, I am not going to be able to discuss specifically this individual or this investigation, nor would I characterize the president's views on an individual or an ongoing investigation. "

　　Carney said President Barack Obama had been briefed by members of his senior staff on the development of the incident, but declined to say whether Obama watched the whistle-blower's video interview released on Sunday by the Guardian newspaper.

　　Carney defended the administration's broad approach to national security and the classified surveillance programs. He said it was "entirely appropriate for a program to exist" to look at the foreign data and foreign potential terrorists.

　　"In general leaks of sensitive classified information that cause harm to our national security interests are a problem," he said.

　　Carney also stressed that the president had made clear the congressional, executive and judicial levels provided oversight over these programs.

　　Edward Snowden, the 29-year-old whistle-blower went public in a video interview with the Guardian after he leaked information on the National Security Agency's secret phone and Internet surveillance programs.

　　According to the video interview conducted in Hong Kong with The Guardian, Snowden previously served in a number of roles in the intelligence community, including as a former technical assistant with the CIA and with several outside contractors.

　　According to the Guardian and the Washington Post reports last Thursday, the NSA and the FBI had been secretly tapping directly into the central servers of nine U.S. internet companies, extracting audio, video, photographs, e-mails, documents and connection logs that enable analysts to track a person's movements and contacts over time.

　　The technology companies all participated knowingly in PRISM operations. They include Microsoft, Yahoo, Google, Facebook, PalTalk, AOL, Skype, YouTube and Apple.

　　By late Thursday night, U.S. National Intelligence Director James Clapper moved quickly to defend the PRISM program, saying the related reports published by the two newspapers contained " numerous inaccuracies."

　　During his visit to the U.S. state of California, Obama on Friday defended the phone and internet surveillance programs, stressing that the tracking of internet activity has not applied to U.S. citizens or people living in the country.

　　The president also insisted that these surveillance programs have been fully authorized by the U.S. Congress and conducted to help prevent terrorist attacks.