Spokesman Gholamhossein Esmaili said two men, Ali Nafariyeh and Mohammadali Babapour, had received 10-year prison sentences for working for the CIA.

Mohammad Amin Nasab was jailed for 10 years for aiding British intelligence.

Mr Esmaili said he would not identify the person sentenced to death because the verdict was subject to appeal.

It was not clear if any of those convicted were among 17 people who Iran's intelligence ministry said had been arrested for spying for the CIA earlier this year.

The ministry alleged they had been collecting information in nuclear and military facilities and in the private sector - allegations that US President Donald Trump dismissed as "totally false".

Mr Esmaili also confirmed on Tuesday that the Iranian authorities had arrested the British-Iranian anthropologist Kameel Ahmady.

Kameel Ahmady's wife said he was arrested at their home in western Iran in August

Mr Ahmady was being investigated on suspicion of "links to foreign countries and institutes affiliated with foreign [intelligence] services", he said.

His wife said in August that he had been arrested at their home in western Iran.

In a separate development, state media quoted Mr Esmaili as announcing that an appeals court had reduced the jail term of Iranian President Hassan Rouhani's brother from seven years to five.

Hossein Fereydoun had been convicted of "receiving bribes", ordered to return any illicitly acquired property, and fined about 310bn riyals ($26.7m at the unofficial market exchange rate), Mr Esmaili added.

It was reported in May that Fereydoun, a close adviser to the president and senior diplomat, had been handed an unspecified jail term for corruption.

The president's supporters had said that the case was politically motivated.