(CNN) -- Germany's chief federal prosecutor has opened a criminal investigation into whether U.S. intelligence services monitored one of German Chancellor Angela Merkel's cell phones, his office said Wednesday.
The office began the investigation Tuesday.
The move comes after media reports last year alleged that the U.S. government eavesdropped on Merkel and other leaders. The revelation prompted outcry from Americans and foreign governments concerned the U.S. was overreaching in its efforts to thwart terrorist attacks.
CNN's Stephanie Halasz contributed to this report