The United Kingdom’s state intelligence agencies allowed the National Security Agency of the United States to store phone, Internet and email data of private U.K. citizens who were not suspected of any wrongdoing, a joint investigation by Channel 4 and The Guardian reveals.

The investigation describes an agreement that U.K. intelligence officials are reported to have entered into with the NSA in 2007 as the “first explicit confirmation that British citizens have been caught up in U.S. mass surveillance programmes.”

Based on documents released by whistle-blower Edward Snowden, the joint investigation has published what it claims is an NSA memo which lays out the terms of the new agreement that it inked in 2007 with the U.K. Liaison Office in Washington. This overturned an earlier rule that protected citizens of the “five-eyes” intelligence sharing alliance comprising the U.S., the U.K., Australia, New Zealand and Canada from surveillance by any of the others.

The new rules gave the NSA the right to retain all the private digital data that it trawled. This was a fundamental change in its policy, the investigation alleges.

Previously, the digital communications of private individuals who were not suspected of wrongdoing and therefore not the targets of surveillance, were taken out of NSA databases, the report notes.

The memo, according to The Guardian, states that “under certain circumstances, it may be advisable and allowable to target second party persons and second party communications systems unilaterally when it is in the best interests of the U.S. and necessary for U.S. national security.”

These revelations will not help the reputation of the U.K.’s intelligence agencies, already bruised by revelations in the media based on leaks from Mr. Snowden of secret mass surveillance of private digital data.

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