US’ NSA collected over 500 million phone call records in 2017: Report

The US National Security Agency collected more than 500 million phone call records of Americans last year, more than triple gathered in 2016, a US intelligence agency report released on Friday said.

The sharp increase to 534 million call records from 151 million occurred during the second full year of a new surveillance system established at the spy agency after US lawmakers passed a law in 2015 that sought to limit its ability to collect such records in bulk. The reason for the spike was not immediately clear.

The tally remained far less than an estimated billions of records collected per day under the NSA's old bulk surveillance system, which was exposed by former US intelligence contractor Edward Snowden in 2013.

The metadata records collected by the NSA include the numbers and time of a call, but not its content.

In a statement, Timothy Barrett, a spokesman at the Office of the Director of National Intelligence, which released the annual report, said the government "has not altered the manner in which it uses its authority to obtain call detail records."

The NSA has found that a number of factors may influence the amount of records collected, Barrett said.

"These factors include the number of Court-approved selection terms - like a phone number - that are used by the target; the way targets use those selection terms; the amount of historical data that providers retain; and the dynamics of the ever-changing telecommunications sector," Barrett said. "We expect this number to fluctuate from year to year."