The US National Security Agency set up secret arrangements with telecom companies outside the US for collecting hundreds of millions of contact lists via email and instant messaging accounts.

The Washington Post, citing documents leaked by whistleblower Edward Snowden, said that the NSA hacked huge numbers of email address books and 'chat buddy lists' of both US and foreign people through a programme operated outside the country, in order to evade local restrictions.

The newspaper said the agency's collection programme intercepts e-mail address books and buddy lists from instant messaging services as they are transmitted across global data links.

"Online services often transmit those contacts when a user logs on, composes a message, or synchronizes a computer or mobile device with information stored on remote servers," said the report.

The newspaper claimed that the agency had access to "a sizable fraction of the world's e-mail and instant messaging accounts" through the programme targeting contact lists rather than individuals.

The NSA collected 444,743 e-mail address books from Yahoo, 105,068 from Hotmail, 82,857 from Facebook, 33,697 from Gmail and 22,881 from unspecified other providers during a single day last year, according to an internal NSA PowerPoint presentation leaked by Snowden.

This "typical daily intake" represents more than 250 million contacts per year.

Even though the data collection takes place outside the US, it accumulates the contacts of many Americans, the report said, citing two senior US intelligence officials. The spy agency accessed contact lists through secret arrangements with foreign telecommunications companies or other services that control Internet traffic, the Post said.

NSA Continues to Defend Itself

A spokesman for the Office of the Director of National Intelligence, which oversees the NSA, told the newspaper that the agency "is focused on discovering and developing intelligence about valid foreign intelligence targets like terrorists, human traffickers and drug smugglers. We are not interested in personal information about ordinary Americans."

A widely criticised NSA programme for collecting nearly all US call records was earlier defended by the agency that said such bulk collection is essential to counter terrorism and serve foreign intelligence department.

The NSA's surveillance practices that included monitoring of vast volumes of Internet traffic and phone records have faced severe criticism across the globe following revelations by Snowden, a former contractor at the agency, who is currently in exile in Russia. The agency was criticised by major US allies including Germany and Brazil.

He leaked top secret documents about NSA's surveillance programmes that tapped telephone conversations and spied on internet activities of citizens, prominent leaders, bureaucrats, businesses and government agencies across the globe.