Germany’s foreign intelligence agency (BND) illegally collected and stored masses of data from innocent German citizens who were unwittingly dragged into mass surveillance dragnets.

A leaked, classified report by the Federal Data Protection Commission (FDPC) found that, for every BND targeted surveillance operation, the intelligence agency was sucking up and storing data of 15 citizens not part of any investigation.

“These infringements of constitutional rights are conducted without any legal basis and thus harm the constitutional right of informational self-determination of [innocent] people,” the FDPC report adds.

Among the BND’s activities, exposed by leaks by whistleblower Edward Snowden, were 18 serious breaches of German fundamental law, according to the leaked FDPC report, and 12 formal complaints.

In addition, the FDPC complained of massive, illegal obstructions to its investigation by the BND, making a satisfactory probe impossible.

Germany’s highest data sheriff ordered the BND to delete data stored in seven databases, information the data regulator said German spies were not entitled to store. The data had been collected using controversial electronic tools developed by the US National Security Agency (NSA), including the Xkeyscore program flagged by Edward Snowden that monitors all internet traffic.

Federal data commissioner Andrea Voßhoff complained her in 60-page report, marked classified by the federal government, that BND constraints on her office’s investigation constituted “grave legal infringements”.

Filtering

Contrary to previous claims by the BND, the FDPC investigation confirmed the agency’s Bad Aibling listening post intercepts not just satellite signals from crisis regions but also taps and processes information taken from communication cables.

However Ms Voßhoff said the BND blocked her agency’s attempts to examine so-called selectors, which identify information such as phone numbers and email addresses used in targeted surveillance.

Opposition politicians in Germany said the report confirmed their worst suspicion: that Germany’s foreign intelligence service is operating outside the law.

“The report cannot be misunderstood, neither in its unusual level of clarity nor in the extent of its criticism,” said Mr Konstantin von Notz, Green Party MP and head of a Bundestag parliamentary committee on the NSA.