Germany’s Foreign Ministry says it has asked Britain to respond to a report that the country’s embassy in Berlin is being used as a covert listening post.

The ministry says in a statement that German Foreign Minister Guido Westerwelle invited in Britain’s ambassador in Berlin following a report in Tuesday’s edition of the Independent newspaper.

The report claimed that documents from the U.S. National Security Agency together with aerial photos and information about past spying activities in Germany suggest Britain could be operating a spy station using equipment housed on the embassy roof.

Germany’s Foreign Ministry said in its statement Tuesday that such a spy station operated from diplomatic premises would be against international law.

The embassy refused to comment on the report.

(AP)