President Barack Obama defended secret US security programs late Monday and rejected comparisons with predecessor George W Bush, even as intelligence tech Edward Snowden warned that more leaks are on the way.
The Obama administration has been on the defensive since last week's dramatic leak of details of two huge operations by the National Security Agency to track US citizens' phone calls and intercept global Internet traffic.
However, a poll yesterday showed 54 percent Americans say Snowden should be prosecuted for the leaks. The USA Today/Pew Research Center poll showed some 38 percent opposed them.
Obama pushed back in a TV interview to charges that he had merely continued with the surveillance policies that ex-president Bush and former vice president Dick Cheney had brought in after the September 11, 2001 attacks.
Obama said on the "Charlie Rose" show on PBS television that the NSA data-gathering programs were carried out with "systems of checks and balances," and insisted that "Congress is overseeing it, federal courts are overseeing it."
"My concern has always been not that we shouldn't do intelligence gathering to prevent terrorism, but rather -- are we setting up a system of checks and balances?"
He also promised that an independent advisory board would review the programs.
Meanwhile Snowden, the 29-year-old former NSA contractor who triggered the firestorm, issued a defiant rebuke to his critics in Washington Monday, and warned of more leaks.
The government has opened a criminal probe into Snowden's acts and partially confirmed his allegations by defending the programs to access Internet data and phone records, saying that they have thwarted dozens of terror attacks.
Snowden insisted he had exposed a dangerous US global surveillance network that threatens the privacy of millions.