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 . The scope of the surveillance dragnet described in the article is enormous . The newspaper says the report , like many previous ones , is based on the Guardian 's reading of documents provided by former U.S. defense contractor Edward Snowden , who admitted leaking documents this month detailing government surveillance programs . Unlike some previous reports , the paper has not published the full documents on which the story was based . A spokesman for the British agency , known as GCHQ , issued a statement saying that in line with long-standing practice , it does not comment on intelligence matters . `` It is worth pointing out that GCHQ takes its obligations under the law very seriously , '' the statement read . `` Our work is carried out in accordance with a strict legal and policy framework which ensures that our activities are authorized , necessary and proportionate , and that there is rigorous oversight , including from the secretary of state , the Interception and Intelligence Services Commissioners and the Intelligence and Security Committee . '' The prime minister 's office at 10 Downing Street also gave a statement saying only , `` We do n't comment on intelligence matters . '' The GCHQ 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 . '' A source with knowledge of intelligence matters said `` intelligence agencies are there to keep citizens safe and the vast majority of data collected is discarded . '' The process used by the GCHQ , the source said , `` scans bulk data for any information that can have national security implication . `` Only information deemed useful for national security is pulled out and examined in more detail . The vast majority of data is not examined or retained . `` The process is legal and governed by the 2000 Regulatory Investigatory Power Act . It is regularly reviewed and authorized by ministerial warrants . This is vital national security work . It 's proportionate and it 's about following terrorist or criminal activity and not about following law-abiding citizens . '' CNN 's Bharati Naik contributed to this report .
BBC : The BBC slams the report as ` ` absolutely false '' The Guardian : The UK agency routinely collects massive communications data . The report is based on information leaked by Edward Snowden . The British government says it does not comment on these matters .