WASHINGTON, June 18 (Reuters) - The Republican head of a congressional panel on Tuesday said officials are concerned that former U.S. contractor Edward Snowden's continued efforts to speak out and release intelligence information pose more risk for the United States.
U.S. House of Representatives Intelligence Committee Chairman Mike Rogers, speaking ahead of a hearing on the disclosures, also said concerns remain that Snowden may not have acted alone in leaking information on the federal government's top-secret surveillance programs.
"Anything that he talks about is dangerous," Rogers said on NBC's "Today" program.
Snowden, a former employee of government contractor Booz Allen Hamilton who worked in a U.S. National Security Agency facility in Hawaii, revealed details to the media earlier this month about the U.S. phone and Internet data tracking. Speaking in an Internet chat on Monday, he defended his actions and vowed to release more details on the extent of the agency's access.
Rogers said that it remains unclear how a low-level outside contractor was able to gain such access to so much classified information. No evidence has emerged yet that anyone else was involved in releasing details about the programs.
"We're a little nervous that some of the things he was trying to do exceeded his capability. So we're curious: how did he get that capability, was somebody helping him trying to download this?" Rogers told NBC.
On Tuesday, the congressional panel will hear from NSA director Keith Alexander, who Rogers said is expected to offer more information on terrorism threats that were halted by the surveillance efforts.
Defenders of the programs have said dozens of potential attacks have been thwarted by intelligence gathered through these surveillance programs, but have said they have not been able to discuss them in detail because that information has been classified.
Late Monday, U.S. President Barack Obama, a Democrat, reiterated his defense of such surveillance, saying there are trade-offs between privacy and national security. Obama added that content of phone calls and emails are not monitored, a statement echoed by Rogers on Tuesday to NBC.
Rogers added that Snowden "believed wrongly ... that the NSA could listen to Americans' phone calls - they cannot - or that they can read Americans' emails - they cannot."
Civil liberties and privacy advocates have blasted the NSA surveillance programs as government overreach that lacks proper oversight, with some groups taking legal action.
The Justice Department is also investigating Snowden's actions, and U.S. officials have vowed to track him down and hold him accountable for the leaks.