Germany expelled the US intelligence station chief in Berlin Thursday over alleged spying by Washington, the government said in a highly unusual move among close NATO allies.
"The representative of the US intelligence services at the embassy of the United States of America has been told to leave Germany," government spokesman Steffen Seibert said in a statement.
Seibert said the demand was based on two formal probes by German federal prosecutors of suspected spying for Washington announced in the last week "as well as outstanding questions over the last several months about the activities of the US secret services in Germany".
"The government takes these developments very seriously," he said.
Seibert said it was "crucial for Germany, in the interest of the security of its citizens and its troops abroad, to work closely on a basis of trust with Western partners, in particular with the USA".
"However, mutual trust and openness are required," he said. "The government remains willing to do this and expects this from its closest partners."
The head of the German parliament's oversight committee, Clemens Binninger, called the expulsion "a reaction to the long-lacking cooperation in efforts to get to the bottom of this affair".
German police on Wednesday searched the Berlin-area home and office of a man who, local media reported, is a German military employee accused of passing secrets to the United States.
The case comes on the heels of news on Friday that a 31-year-old German BND intelligence service operative had been arrested, suspected of having sold over 200 documents to the CIA.
The documents reportedly included papers on a German parliamentary panel probing mass surveillance activities by the US National Security Agency, whose targets have alleged included Chancellor Angela Merkel's mobile phone.