Spain has opened a preliminary inquiry into allegations that it has been targeted by the US for surveillance, according to the country's prosecutor's office.
The inquiry will attempt to determine whether a crime was committed and whether Spain should consider opening a formal investigation.
On Monday, El Mundo newspaper claimed 60 million Spanish phone calls had been tracked by the Nation Security Agency in one month alone.
Spain has said it's unaware of any US spying and that it is confident Washington will provide a full explanation.
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