The US government said it only searched for detailed information on calls involving fewer than 300 specific phone numbers among the millions of phone records collected by the national security agency (NSA) in 2012.
Reuters reported that the unclassified paper was circulated within the government by US intelligence agencies in a bid by spy agencies and the Obama administration to clear allegations that it went beyond the norm while investigating potential militant threats.
The paper also mentioned the latest NSA programme, dubbed Prism, which collects data from Internet firms what the paper says are emails of foreigners who might be of interest to counter terrorism or counter-proliferation investigators.
According to the paper, the data collected from both the programmes prevented terrorist attacks in the US and over 20 other countries globally.
Last week, NSA head Keith Alexander defended the surveillance programme, Prism, by saying that it helped to prevent dozens of possible attacks both in the country and abroad.
Alexander said dozens of terrorist events have been prevented in the US and abroad.
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