London (CNN) -- Britain's equivalent to the U.S. National Security Agency, the Government Communications Headquarters, has tapped into many of the world's key international fiber optic cables and is routinely downloading and analyzing vast quantities of Internet and phone traffic, sharing the data with the NSA, The Guardian newspaper reported Friday. The NSA slammed the report as "absolutely false." "Any allegation that NSA relies on its foreign partners to circumvent U.S. law is absolutely false. NSA does not ask its foreign partners to undertake any intelligence activity that the U.S. government would be legally prohibited from undertaking itself," NSA spokeswoman Judith Emmel said.
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NEW: The NSA slams the report as "absolutely false"
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The Guardian: The UK agency routinely downloads massive communications data
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The report is based on documents leaked by Edward Snowden
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The British government says it does not comment on intelligence matters
The @placeholder is one of the three UK intelligence agencies and, according to its website, forms a "crucial part of the UK's national intelligence and security machinery."