German Foreign Minister Guido Westerwelle has called the British ambassador on Tuesday over claims of spying by the British embassy in Berlin.

According to the foreign ministry, German officials told Ambassador Simon McDonald that "the interception of communications from the premises of a diplomatic mission would be an internationally wrongful act." No further details of the meeting have so far been made public.

London-based Independent newspaper on Tuesday reported that Britain could be operating a "covert listening station" in Berlin using the equipment housed on its embassy's roof.

The report said the equipment could be used to eavesdrop on cell phone conversations and to supervise the communications in government offices.

The report came as German officials are outraged by allegations that U.S. intelligence may have targeted Chancellor Angela Merkel's cell phone.

Last week, Berlin had summoned the U.S. ambassador over the eavesdropping allegations.

"The latest showed that we should also make a no-Spy agreement with Great Britain," said Wolfgang Bosbach, a German lawmaker from Merkel's party. "It is regrettable that such agreements between partners are necessary at all, but a complete espionage is totally unacceptable."