German Chancellor Angela Merkel placed an irate call to U.S. President Barack Obama Wednesday after reports surfaced that U.S. intelligence agencies were monitoring her mobile phone.

During the call, Merkel "made clear that she unequivocally disapproves of such practices, should they be confirmed, and regards them as completely unacceptable," notably harsh language for an official statement from spokesman Steffen Seibert. "We swiftly sent a request to our American partners asking for an immediate and comprehensive clarification." 

Merkel, who recently won a strong third-term victory from the German electorate, is arguably Europe's paramount leader and the most powerful woman in the world. The governments of France, Brazil and Mexico have strongly protested alleged U.S. spying on their leaders as well in recent weeks.  

“The United States is not monitoring and will not monitor the communications of the chancellor," White House Press Secretary Jay Carney said right after the story broke.

The German government wouldn’t confirm how they obtained the information about the U.S. spying on Merkel’s phone, but German magazine Der Spiegel said the information came from them, the AP reported.

Seibert said the story, if true, would represent a "serious breach of trust."

"Among close friends and partners, as the Federal Republic of Germany and the U.S. have been for decades, there should be no such monitoring of the communications of a head of government," he said in Berlin.

The news comes just one day after James R. Clapper, U.S. director of national intelligence, denied reports that the U.S. had spied on more than 70 million phone calls in France over a 30-day period, according to the BBC. Clapper has been caught lying to members of Congress about surveillance before.