The American National Security Agency has been spying on nearly 100,000 computers around the world using secretly inserted USB drives, The New York Times reported on Tuesday.
The technology used enables the agency to carry out surveillance on computer networks and conduct cyber-attacks, even if they are not connected to the internet.
Using circuit boards and USB drives that can transmit radio frequencies, computer data can be sent to a relay station several miles away.
"What's new here is the scale and the sophistication of the intelligence agency's ability to get into computers and networks to which no one has ever had access before," James Andrew Lewis, the cyber security expert at the Centre for Strategic and International Studies in Washington, told The New York Times.
"Some of these capabilities have been around for a while, but the combination of learning how to penetrate systems to insert software and learning how to do that using radio frequencies has given the U.S. a window it's never had before."
Citing NSA documents, officials and technology experts, The Times reports that the agency has been using this technology since 2008.
"N.S.A.'s activities are focused and specifically deployed against — and only against — valid foreign intelligence targets in response to intelligence requirements," Vanee Vines, an agency spokesperson, said in a statement.
"We do not use foreign intelligence capabilities to steal the trade secrets of foreign companies on behalf of — or give intelligence we collect to — U.S. companies to enhance their international competitiveness or increase their bottom line."
The latest revelations in the NSA spying scandal come just days before President Barack Obama announces a proposed revamp of the agency. In a speech this Friday, Obama is expected to unveil sweeping reforms that could impose significant limitations to the way the agency collects and stores data.