British intelligence agency GCHQ secretly accessed fibre-optic cables carrying huge amounts of internet and communications data, according to documents released by National Security Agency (NSA) whistleblower Edward Snowden.
The agency is able to tap into and store data from the cables for up to 30 days so it can be analysed under an operation codenamed Tempora, The Guardian reported.
GCHQ would not comment on intelligence matters but insisted it was "scrupulous" in complying with the law.
The newspaper said there were two principal components to the agency's surveillance programme, called Mastering the Internet and Global Telecoms Exploitation.
It claimed the data was shared with the organisation's US counterpart the National Security Agency (NSA).
The information is the latest leak from Mr Snowden, the whistleblower responsible for a string of disclosures about US intelligence operations.
More top news
The guitarist is reportedly in full-time care in Sydney and will not be joining the band for their forthcoming album.
Author Irvine Welsh issued an expletive-laden attack after George Osborne referenced one of his characters in his party conference speech.
Cheryl Cole has been named as the "most dangerous celebrity" online measured by the amount of malicious websites linked to a star's name.