Berlin: Germany`s Interior Minister Thomas de Maizière has said that an explanation has been sought from the US intelligence services over its contact with a German man arrested last week on suspicion of being a double agent, the media reported Sunday.
"I expect everyone to cooperate promptly to clear up these allegations - with quick and clear comments from the US as well," Thomas de Maizière was quoted as saying by German tabloid Bild.
The White House and state department have so far declined to comment on the arrest of a 31-year-old employee of Germany`s BND foreign intelligence agency, who has admitted passing documents to a US contact, the Guardian reported citing intelligence and political sources.
The documents includes information about a parliamentary committee looking into allegations by the former US intelligence contractor Edward Snowden that Washington carried out major surveillance in Germany, including monitoring the phone of Chancellor Angela Merkel.
The case risks further straining ties with Washington, which have been sorely tested by revelations last year of large-scale snooping on Germany by the US National Security Agency (NSA).
Surveillance is a sensitive issue in a country where the memory of the Nazis` Gestapo secret police and communist East Germany`s Stasi means the right to privacy is treasured.
Thomas de Maizière called it a "very serious case" that had to be investigated fully to "gauge the scale of the alleged spying and especially answer the question of who was involved".
The US ambassador was called in on Friday to hear Berlin`s request for an explanation and the foreign minister, Frank-Walter Steinmeier, said Sunday that it was in Washington`s own interests to help with the "quickest possible clarification of the facts".
The former US secretary of state Hillary Clinton, who was in Berlin promoting her new book, said Sunday it was "clearly a serious issue" but she hoped the affair would not "undermine the necessary cooperation which exists between us".