A witness told a German parliamentary inquiry on Thursday that America's NSA was fed filtered data from an internet exchange point in Frankfurt, after an OK from the Chancellery in Berlin.

The Eikonal project leader within Germany's BND foreign intelligence agency - identified only as S.L. - said the exchange's own operator had legal doubts, but was convinced once confirmation came from the-then chancellery.

Germany's federal intelligence service (BND) delivered filtered information from 2004 until 2008, when the "Americans saw that we could not extract anything more for them," said the witness, who was quoted by Germany's main news agency DPA.

Over that period, Germany was first governed by a center-left coalition headed by Social Democrat Chancellor Gerhard Schröder, and from October 2005 by Chancellor Angela's first grand coalition cabinet.

Anchored in Germany's constitution are strict data privacy laws in reaction to the Hitler dictatorship and Stasi eavesdropping in former communist East Germany.

The project leader said the BND used NSA equipment and know-how to tap the hub's lines, including telephone calls, for data which passed through multiple "cascade" filters and then to a BND/NSA facility at Bad Aibling near Munich.

Several hundred items were eventually forwarded each year to the NSA after checking by staff to make sure data about Germans had been removed

In October, the newspaper Süddeutsche Zeitung in an investigative report said these filters had not worked sufficiently to filter out all data on Germans.

Mass NSA monitoring of mobile phone operators

The website The Intercept claimed on Thursday that papers from the US whistleblower Edward Snowden showed that the NSA spied on hundreds of mobile phone operators.

In an operation codenamed "AURORAGOLD," the NSA kept watch on 1200 email accounts of operators, looking for security weaknesses in their systems, gleaned especially when they exchanged advice on roaming for customers abroad.

During 2012, information was gathered in this way from more than 70 percent of the mobile operators worldwide, The Intercept said, adding the newly known factor was the mass scale of the observation.

Last year, it emerged that the NSA - deciphering the widely used GSM wireless standard - had tapped into one of Merkel's mobile phones.

ipj/jr (dpa, AFP)