The group German Agro Action has asked for a formal inquiry after learning it was spied upon by Germany's foreign intelligence service, the BND, in Afghanistan. So why were the spooks listening in on aid workers?
Germany's Big Brother has been watching, listening and reading
The charity, which is aimed at fighting hunger and has been active in Afghanistan since 1980, directed its appeal directly to Germany's conservative Chancellor Angela Merkel.
"We are astonished and puzzled to learn that a German constitutional body should have kept tabs on an independent German aid organisation," German Agro Action General Secretary Hans-Joachim Preuss wrote in a letter to Merkel.
He said the group had learned from the BND itself that the intelligence service had secretly monitored at least 2000 e-mails, fax messages and telephone conversions within the charity between October 2005 and April 2008.
Preuß asked Merkel to ensure that the surveillance was discontinued and said that the charity was consulting with lawyers as to whether the BND might have violated the German constitution.
In April of this year, it emerged that the BND had also intercepted emails between a German journalist and Afghanistan's Economics Minister in 2006.
The charity wants the BND to focus on prevent acts of Taliban insurgency
Other German Agro Action employees said the revelations had hurt the charity's ability to do its work.
"It will be more difficult for us to get information from other non-governmental organisations if one thinks one might be listened to," the official in charge of German Agro Action's Afghanistan operations, Nic Lee, told AFP news agency.
And he questioned the logic behind the surveillance. In a statement to the dpa news agency, Lee said it was "a transparent waste of taxpayers' money to spy on organizations whose reports are public anyway."
"The German secret service should concentrate on the Taliban instead," Lee told dpa.
The deputy chairman of parliamentary intelligence oversight committee, Max Stadler of the opposition Free Democrats (FDP), also told a German radio station that the BND should be called to testify about the affair in the German Bundestag.
These have not been good weeks for BND head Uhrlau
The latest revelations increased the heat on BND head Ernst Uhrlau, who's still reeling from the arrest of three BND operatives in Kosovo last month.
The operatives were part of a covert mission so secret that even German government representatives in Kosovo knew nothing of it.
They were arrested after they visited the site of a bomb attack on an EU target in the city of Pristina. The three men were later released, but the controversy raised further questions about the legality and efficiency of BND operations.
Green parliamentarian Hans-Christian Stoebele has joined colleagues from the FDP and the Conservatives Bavarian sister party, the CSU, in calling for further investigations.
"We have to find out what's gone out of control there," Stroebele told the dpa news agency.
The main spokesman for the current government, on the other hand, has said Uhrlau enjoys the "unrestricted trust" of the Chancellor and the Chancellor's Office.