BERLIN (Reuters) - Germany's Foreign Ministry said on Tuesday it had asked the British ambassador to come and discuss a report that Britain was operating a covert spying station in Berlin, using hi-tech equipment housed on the embassy roof.

"At the instigation of Foreign Minister (Guido) Westerwelle, the British ambassador was asked to come for a talk at the Foreign Ministry," the ministry said in a statement.

"The director of the European department asked for an explanation of current reports in British media and indicated that tapping communications from a diplomatic mission would be a violation of international law."

Documents leaked by former United States National Security Agency contractor Edward Snowden show that Britain's surveillance agency is operating a network of "electronic spy posts" from within a stone's throw of the Bundestag and German chancellor's office, British newspaper The Independent reported.