The overseas wiretapping activities have been a source of controversy since it was disclosed in December 2005 that Bush had secretly authorized the NSA to override existing laws and begin monitoring the international phone calls and e-mails of U.S. residents. Critics, including some members of Congress, have described the eavesdropping as a violation of laws passed in the 1970s that required court warrants before communications of U.S. residents could be monitored.
Bush and Hayden, who headed the NSA from 1999 to 2005, have repeatedly defended the legality of the program, characterizing it as a carefully targeted operation.
"We're going after very specific communications that our professional judgment tells us we have reason to believe are those associated with people who want to kill Americans," Hayden said in a speech defending the program in 2006.
It is not clear whether the abuses alleged by Kinne and Faulk occurred as part of the sweeping Terrorist Surveillance Program authorized by Bush in the aftermath of the Sept. 11 attacks or were tied to more narrow military intelligence operations focused on protecting U.S. forces.
An NSA spokesman said the agency "takes its legal responsibility seriously" and operates "in strict accordance with U.S. laws and regulations and with the highest standards of integrity and lawful action."
"Some of these allegations have been investigated and found to be unsubstantiated," the NSA spokesman said. "Others are in the investigation process."
Congress overhauled the foreign intelligence surveillance laws this year to give the government greater latitude to track targets overseas. But the law still imposes strict protections for U.S. citizens abroad and requires the government to delete or block information that isn't for valid intelligence purposes.
"At NSA, the law was followed assiduously," said Mark Mansfield, a spokesman for Hayden, who became CIA director in 2006. "The notion that Gen. Hayden sanctioned or tolerated illegalities of any sort is ridiculous on its face."
An intelligence official who was not authorized to discuss the matter publicly and requested anonymity said the inspectors general at the Army and the NSA had investigated Kinne's allegations and "were not able to substantiate them."
Civil liberties groups said the linguists' accounts raise questions about safeguards for citizens. "The NSA used its surveillance powers to intentionally collect the personal communications of innocent Americans," said Jameel Jaffer, director of the American Civil Liberties Union's National Security Project.