In June, The Guardian reported that Tempora — the surveillance program that is essentially the UK's version of PRISM — was tapping into undersea fiber-optic lines to access massive amounts of emails, social-media posts, video chats, and other online data. On Friday, the German newspaper Süddeutsche published a new story that claims Britain's Government Communications Headquarters (GCHQ) executed the spying program with the help of Verizon, BT, and Vodafone. In the process, these telecommunications companies and others have reportedly given the UK intelligence agency unrestricted access to the data that passes through their fiber-optic cables.

Süddeutsche's source for all this? Documents it says were supplied by Edward Snowden, the former National Security Agency (NSA) contractor behind the PRISM leaks. The documents are reportedly from 2009 and list Verizon, BT, and Vodafone as taking part in Tempora along with other UK telecom companies Global Crossing, Level 3, Viatel, and Interoute. Each of the companies — which operate key fiber-optic cables that cross the ocean floor — declined to comment to The Guardian on Tempora or their alleged collaboration with the GCHQ. According to the UK publication, data collected in Tempora is shared between the GCHQ and the NSA. The Guardian has also previously reported that, in addition to enormous amounts of web data, Tempora also intercepts some 600 million "telephone events" every day.