An NSA and GCHQ surveillance programme - dubbed Treasure Map - grants US and British spooks access to the networks of German telcos such as Deutsche Telekom, according to a new stash of leaked documents from Edward Snowden.
Der Spiegel published the latest revelations today. However, Deutsche Telekom reportedly said it had found no evidence of such tampering on its system.
"We are looking into every indication of possible manipulations but have not yet found any hint of that in our investigations so far," a spokesman at the company told Reuters.
He added: "We're working closely with IT specialists and have also contacted German security authorities. It would be completely unacceptable if a foreign intelligence agency were to gain access to our network."
The Register sought comment from the telco, but it hadn't immediately got back to us at time of writing.
The Treasure Map programme was described by Snowden as "a 300,000 foot view of the internet" in a New York Times story published in November last year.
Der Spiegel said today that the latest leaked documents from the former NSA sysadmin showed that spooks planned to map routers, smartphones, fondleslabs and computers on its massive snooping system.
Analysts are apparently told to "map the entire internet - Any device, anywhere, all the time." And surveillance agencies who are part of the so-called FiveEyes fraternity from the UK, Canada, Australia and New Zealand work with the US on Treasure Map.
Those eavesdroppers can install and use the computer program, the newspaper claimed. "One can imagine it as a kind of Google Earth for global data traffic, a bird's eye view of the planet's digital arteries," Der Spiegel said.
According to the documents seen by the newspaper, the Treasure Map system has already tapped into the networks of former state-owned Deutsche Telekom and smaller German carrier Netcologne, and - by extension - the end devices of those companies' subscribers.
In June, the German government said it would cancel its contract with US telecoms provider Verizon, citing spying fears.
It said at the time:
The ties revealed between foreign intelligence agencies and firms in the wake of the US National Security Agency affair show that the German government needs a very high level of security for its critical networks.
It was reported that Deutsche Telekom would pick up where Verizon leaves off after having its contract terminated by the German government. ®