Belgium and the Netherlands have joined Austria and Luxembourg in getting really rather upset that German spies, er, spied on them.

But what really as the Belgians worked up is that the information collected by the German intelligence agency (BND) was passed on to the NSA.

On Friday, Belgium's justice ministry announced it is investigating the matter. “If it should emerge that the reports of wide-scale eavesdropping by the German secret services are correct, Germany will have to provide an explanation,” said telecoms minister Alexander de Croo.

"A probe has been opened," Dutch government spokesman Ward Bezemer added.

Meanwhile, in Berlin, German Chancellor Angela Merkel has said she will testify before two German parliamentary inquiries.

Earlier this month, Austrian MP Peter Pilz publicly accused Deutsche Telekom of listening in on telephone and internet lines from Vienna, Luxembourg, Prague, Moscow and Ankara. However Deutsche Telekom told The Reg it was “obligated to cooperate with the BND as set out in the Federal Intelligence Service Act.”

The mass surveillance program, codenamed Operation Eikonal, allowed the BND to access fiber optic cables at the Deutsche Telekom switching center in Frankfurt. Pilz said the spying has been going on for at least 10 years, and questions must be answered. He has called for a parliamentary inquiry into spying activities "to the detriment of Austria."

With EU institutions based in Brussels, it is likely Belgium was indeed a target of espionage activities. When Belgian telco Belgacom was hacked in 2013 it was widely assumed to have been the work of GCHQ seeking out sensitive information on Euro nations. Strangely enough, the Belgians didn’t feel man enough to take on the UK. ®