It did not say whether those detained were still under arrest.

“These spies were taking earth samples in Iran’s central desert, where the Revolutionary Guards’ aerospace missile exercises were conducted,” state TV said.

The TV showed footage of Giles Whitaker and his family in central Iran, where the British diplomat appeared to be taking ground samples. The TV said it was near an area that a missile test was taking place.

“Whitaker was expelled from [the area] after apologising” the TV report said.

One of those detained was identified by state TV as the husband of Austria’s cultural attaché in Iran. It also showed a picture of a third foreigner, identifying him as Maciej Walczak, a university professor in Poland.

The TV report ran footage allegedly showing Maciej Walczak and three colleagues collecting earth samples in another area after visiting Iran on a scientific exchange programme. It said their sample collection also coincided with a missile test in Iran’s southern Kerman province.

Iran’s elite Revolutionary Guards have arrested dozens of dual nationals and foreigners in recent years, mostly on espionage and security-related charges.

Rights groups have accused the Islamic Republic of trying to win concessions from other countries through arrests on security charges that may have been trumped up. Tehran denies arresting people for political reasons.

(Writing by Parisa Hafezi; Editing by Chris Reese and Sandra Maler.)