The US NSA has reportedly tapped the data links used by Google and Yahoo in a bid to transfer mammoth amounts of email and other user data among its data centres overseas, the latest Snowden leak reveals.
Google claimed that it was not aware of the suspected activity, and stressed urgent requirement for reform.
Google chief legal officer David Drummond was cited by the Washington Post as saying that the company has long been concerned about the possibility of this kind of snooping and has not provided the government with access to its systems.
"We are outraged at the lengths to which the government seems to have gone to intercept data from our private fiber networks, and it underscores the need for urgent reform," Drummond said.
However the NSA's director reported that the agency had not accessed to the companies' computers.
Documents also claim that millions of records were collected everyday from the internal networks of the internet majors.
Yahoo spokesperson said: "We have strict controls in place to protect the security of our data centres, and we have not given access to our data centres to the NSA or to any other government agency."
As part of the PRISM programme, the NSA collects massive volumes of online communications records by legally inducing US tech firms, including Yahoo and Google, to turn over any information that overlaps with search terms approved by the court.
Recently, the agency has been slammed by Mexico over alleged snooping on email account of ex-Mexican President Felipe Calderon in 2010, saying such actions would not be tolerated and they breach international law.