"At the instigation of Foreign Minister (Guido) Westerwelle, the British ambassador was asked to come for a meeting at the Federal Foreign Office," a foreign ministry statement said.
It added that the ministry's head of European affairs had "asked for an explanation of current reports in British media and indicated that tapping communications from a diplomatic mission would constitute a violation of international law".
The request, which was not a summons but is unusual between European Union partners, was prompted by a report in the Independent newspaper today of a spy post not far from Chancellor Angela Merkel's office in Berlin.
The Independent report said Britain's electronic eavesdropping centre GCHQ (Government Communications Headquarters) appeared to be using high-tech equipment on the embassy roof to intercept German data.
More From This Section
The broadsheet cited aerial photographs and information about past spying activities in Germany, as well as documents provided by Edward Snowden, the former NSA contractor who has fled to Moscow.
An eavesdropping post on the roof of the US embassy in Berlin is believed to have been shut down last week as Washington scrambled to limit damage from the row, the Independent reported.
Merkel rolled out the red carpet for British Prime Minister David Cameron in April, inviting not only him but his family to stay overnight at the German government's 18th century guest house, some 80 kilometres (50 miles) north of Berlin.
Cameron alarmed fellow EU leaders in January when he set out plans to wrest back powers from Brussels, and to then put Britain's reshaped membership to an in-out referendum by the end of 2017.