Transcripts of a German parliamentary inquiry into the NSA have been leaked by WikiLeaks.

The searchable files cover 10 months of hearings, which have not been as open as authorities would have us believe, according to WikiLeaks.

"Despite many sessions being technically public, in practice public understanding has been compromised as transcripts have been withheld, recording devices banned and reporters intrusively watched by police," according to WikiLeaks.

"WikiLeaks is releasing 1,380 pages of transcripts from the unclassified sessions, covering 34 witnesses – including 13 concealed witnesses from Germany's foreign intelligence agency, the Bundesnachrichtendienst (BND)," the Julian Assange-fronted whistleblower site said in a statement. "The transcripts cover from the start of the inquiry in May 2014 through to February 2015."

Calls for an inquiry into NSA spying on Germany grew in the second half of 2013, in the wake in leaks from Edward Snowden on mass surveillance of German citizens, and particularly after it emerged that the US had specifically targeted Chancellor Angela Merkel's phone. The inquiry was set up in March 2014, tasked with investigating surveillance activities by the United States on German soil and to what degree German agencies have been complicit in this spying.

During the inquiry it emerged that the German Chancery sent a letter to the chief exec of Deutsche Telekom calling for help with the continuous mass surveillance of German and international internet and telecommunications data at Deutsche Telekom's Frankfurt exchange point. This operation, codenamed "Eikonal", saw these intercepts then pass from the BND to the NSA.

More recently, it emerged that the NSA was passing on selectors – IP addresses, emails, and mobile phone numbers – for spying. Targets included members of the French government and European industry, including the European Aeronautic Defence and Space Company (EADS) and Eurocopter. Airbus, another target of alleged spying, has launched a lawsuit.

The NSA also reportedly wanted the BND to spy on Siemens over its alleged business with Russian intelligence. The BND-NSA co-operation on surveillance was ostensibly about fighting international terrorism but much of what happened in practice seemed to be about harvesting geo-political intelligence, if not downright economic espionage.

Some weeks into the inquiry, a German intelligence agency staffer was arrested after allegedly being caught spying on behalf on the US.

Highlights of the leaked files include how the BND tap fibre optic cables from the German intelligence officer who does the tapping. WikiLeaks is saying it released the files in order to inform the debate.

Surveillance is a sensitive issue for Germany because of the history of spying by the Stasi secret police in Communist East Germany as well as the long shadow of the Nazi era. As a result, Germans tend to guard their privacy more jealously than other western Europeans. ®