The German magazine Der Spiegel reported Wednesday that German Chancellor Angela Merkel strongly suspects her mobile phone has been under American surveillance “for years.”

The magazine’s story, which did not provide any details, lists well-known American security researcher Jacob Appelbaum as the lead author. (Appelbaum currently lives in Berlin.)

The article adds that “Spiegel research” was shared with the Federal Office for Information Security and the German Federal Intelligence Service (BND), the rough equivalent of the American CIA and National Security Agency (NSA). Following this unspecified research, the magazine noted that “Berlin seems to have found their suspicions plausible enough to confront the US government.”

Steffen Seibert, Merkel’s spokesperson, told the magazine that the German government finds such tactics “totally unacceptable,” adding that "such practices must immediately be put to a stop."

White House spokesman Jay Carney unequivocally told reporters that such surveillance was not continuing, but he did not directly deny the allegations of past conduct.

"The president assured the chancellor the United States is not monitoring and will not monitor the communications of the chancellor," he said.

The United States is believed to have targeted other allies recently, including France, Mexico and Brazil. Such charges are often met by carefully worded non-denials, and so the Office of the Director of National Intelligence (ODNI) this week denied that the NSA has collected millions of "recordings" of French telephone calls—though it did not deny collecting the millions of pieces of phone call metadata and text messages that were actually described by French paper Le Monde.

“While we are not going to discuss the details of our activities, we have repeatedly made it clear that the United States gathers intelligence of the type gathered by all nations,” James Clapper, the ODNI’s head, wrote in a statement. “The US collects intelligence to protect the nation, its interests, and its allies from, among other things, threats such as terrorism and the proliferation of weapons of mass destruction. The United States values our longstanding friendship and alliance with France, and we will continue to cooperate on security and intelligence matters going forward.”