The State Department also said Swiss diplomats, who represent US interests in Tehran in the absence of diplomatic ties, asked Iran on Saturday for permission to see alleged spy Amir Mirzai Hekmati, but were denied their request.
“We are aware of press reports that a closed-door trial has begun against Mr Hekmati,” State Department deputy spokesman Mark Toner told reporters.
“We’ve seen this story before with the Iranian regime falsely accusing people of being spies and then holding innocent foreigners for political reasons.”
He urged Iran to grant the Swiss access to Hekmati and to release him “without delay.”
Iran’s Fars news agency reported that the prosecutor in Hekmati’s case called for the “maximum punishment” — presumably the death penalty — if he is convicted.
Confessions extracted from Hekmati “have made it clear that the accused cooperated with the Central Intelligence Agency and acted against (Iran’s) national security,” the prosecutor was quoted as saying.
Hekmati, a 28-year-old former US Marine born in the United States to an Iranian immigrant family, was shown on Iranian state television mid-December saying in fluent Farsi and English that he was a CIA operative sent to infiltrate the Iranian intelligence ministry.
The United States called for his release following his television appearance.
US-Iranian ties have been fraught with tension since the 1979 Islamic revolution that overthrew the pro-Western shah. A series of detentions of Americans in Iran have further strained the relationship.
