The United States National Security Agency (NSA) had been illegally collecting 250 million Americans' electronic communications annually with no terror link due to a technological error, the officials said.
The U.S. government was not aware of the improper collection of emails until 2011 due to NSA's incapability of breaking down huge chunks of data, the Politico reports.
Foreign Intelligence Surveillance Act (FISA) court had demanded a halt to the malpractice in 2011 claiming that the sheer volume of transactions acquired by NSA was such that any meaningful review of the entire body of the transactions was not feasible.
Director of National Intelligence James Clapper will release three documents revealing the extent of the error, the report added.
The NSA administrative officials have claimed that Congress was very much aware that some Americans would inadvertently have their communications intercepted, when it authorized the surveillance programs in 2008.
The officials, meanwhile, said that the problem was technological and not malicious.
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The NSA had been collecting broad batches of e-mails by taking screenshots of entire inbox, even though the targeted e-mail address might have appeared in only one of the messages, the officials said.
The process used by NSA was called the 'Upstream Collection' that collected communications that are transiting the Internet, opposed to communications that were collected at either end by the Internet Service Provider.
The FISA court had concluded in 2011 that there was no way to properly monitor the communications acquired via upstream collection and had banned the process.