Iran says it has arrested 17 spies who it says were working for the CIA, and sentenced some of them to death.
The intelligence ministry said the suspects had been collecting information in the nuclear, military and other sectors.
US President Donald Trump has dismissed the Iranian allegations, saying they are “totally false”.
Washington and Tehran are at loggerheads over Iran’s nuclear programme and tensions have grown.
Mr Trump last year abandoned the international nuclear deal with the Iranians, and the US has imposed sweeping economic sanctions on them.
In recent weeks, the two countries came close to military conflict in the Gulf.
Speaking shortly after the Iranian announced on the arrests, Mr Trump said: “It’s getting harder for me to want to make a deal with Iran.”
What do we know about the ‘spying case’?
Iran says the spies who are alleged to work for the US Central Intelligence Agency were arrested over a 12-month period up until March this year.
The 17 were all Iranians working in “sensitive centres” in military and nuclear facilities and the private sector who had acted independently of each other, a top Iranian intelligence official told reporters.
He did not say how many had been sentenced to death or when the sentences had been handed down.
“Sentences for these spies have been issued, some of whom are to be put to death as ‘corruptors on earth’ [a charge punishable by death under Islamic rules in Iran],” the head of the intelligence ministry’s espionage department was quoted as saying by the Iranian Students News Agency (ISNA).
