A suspected double agent under arrest in Germany appeared to have been working for the CIA for two years, investigators said after allegedly uncovering an American spying device on his computer.
"All the evidence suggests that he was working for the Americans," an unnamed senior security official told the Frankfurter Allgemeine Zeitung.
The country's top security official demanded a full American response to the German investigations.
"I expect everyone now to assist quickly in clearing up the accusations - and quick and clear statements, from the US too," Thomas de Maiziere, the Interior Minister said.
The Foreign Ministry summoned the American ambassador on Saturday even though German authorities have confirmed only that a 31-year-old man is under arrest. The man, who is severely disabled, worked in the Foreign Relations department of Germany's BND intelligence service, where he had access to classified documents and information about agents abroad.