The US National Security Agency (NSA) broke privacy rules and overstepped its legal authority thousands of times in the past two years, according to documents leaked by Edward Snowden.
The incidents resulted in the unauthorised electronic surveillance of US citizens, according to documents published by the Washington Post. Mr Snowden, a former NSA contractor, has leaked top secret documents to the US and British media.
On Thursday, the Washington Post posted on its website a selection of documents it said had been provided by Mr Snowden, who fled the US in June after providing documents detailing NSA surveillance programmes to the Guardian and Washington Post newspapers.
The documents purport to show that the unauthorised interception of telephone calls and emails of Americans and foreign nationals on US soil resulted from errors and departures from standard agency processes, including through a data collection method that a secret US surveillance court later ruled unconstitutional.
The documents offer more detail into the agency practices than is typically shared with members of Congress, the US justice department, and the Office of the Director of National Intelligence.
An internal audit dated May 2012 counted 2,776 incidents over the previous 12 months of unauthorised data collection. The rate of violations grew significantly each quarter, from 546 in the second quarter of 2011 to 865 in the first quarter of 2012.
It is unclear how many individuals were subjected to unauthorised surveillance.
NSA auditors speculated the number of incidents jumped in the first quarter of 2012 because a large number of Chinese surveillance targets visited the US for the Chinese New Year. NSA surveillance of foreign nationals while they are on US soil is restricted.
According to an internal NSA audit report detailing the incidents in the first quarter of 2012, the majority occurred due to “operator error”, usually from failure to follow procedures, typographical errors, insufficient research information, or workload issues.
