The US National Security Agency has been authorised to intercept information "concerning" all but four countries worldwide, according to top-secret documents.
"The United States has long had broad no-spying arrangements with those four countries — Australia, Britain, Canada and New Zealand," the Washington Post reports.
Yet "a classified 2010 legal certification and other documents indicate the NSA has been given a far more elastic authority than previously known, one that allows it to intercept through US companies not just the communications of its overseas targets but any communications about its targets as well."
The certification — approved by the Foreign Intelligence Surveillance Court and included among a set of documents leaked by former NSA contractor Edward Snowden — says 193 countries are "of valid interest for US intelligence."
The certification also let the agency gather intelligence about entities such as the World Bank, the International Monetary Fund, European Union, and the International Atomic Energy Agency, the report says.
The report stresses the NSA did not necessarily target nearly all countries but had authorisation to do so.
Stanford Center for Internet and Society director of civil liberties, Jennifer Granick, told ZDNet that American data could be swept up by the NSA, and many of the decisions on which US-based data goes international is made by service providers themselves.
"They have off shore data centers for latency/redundancy purposes and so US data might travel internationally to be stored there," she said.
"There are some rules about how they can use both American and non-US person data, but the rules are protocols internal to the Executive Branch or even the agency, and they are very, very liberal."
It should come as cold comfort to Germany, which was outraged by revelations last year that the NSA eavesdropped on Chancellor Angela Merkel's mobile phone, as well as about wider US surveillance programs of internet and phone communications.
The privacy issue is a particularly sensitive one in formerly divided Germany.
Ties between Washington and Europe more broadly, as well as other nations such as Brazil, have been strained since the revelations, despite assurances from US President Barack Obama that he is ending spy taps on friendly world leaders.
Snowden, a 30-year-old former NSA contractor was granted temporary asylum by Russia last August after shaking the American intelligence establishment to its core with a series of devastating leaks on mass surveillance in the US and around the world.