The United States on Thursday called an Iranian charge of espionage against an American journalist "baseless" and "without foundation."
State Department spokesman Robert Wood said that the United States is "deeply concerned about the Iranian announcement" of the charge against Roxana Saberi.
Saberi, a 31-year-old dual American-Iranian citizen, was arrested in late January and initially accused of working without press credentials. An Iranian judge leveled a far more serious allegation on Wednesday, charging her with spying for the United States.
The new charge was a setback at a time when US President Barack Obama has expressed willingness to talk with Iran after many years of rocky relations under the former US administration.