Iran's Revolutionary Guards have detained several foreigners, including Britain's second most senior envoy in Tehran, for alleged acts of spying such as taking soil samples in restricted areas, state television reported on Wednesday.

It did not elaborate on when they were arrested or whether they were still under arrest. Britain said the reports were "completely false".

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

Iranian state TV showed what it said was 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 by the Guards.

"Whitaker was expelled from the city after apologising (the authorities)," the TV report said.

However, a spokesperson for Britain's Foreign Office said: "Reports of the arrest of a British diplomat in Iran are completely false." read more

Samuel Heath, UK spokesperson to the United States, tweeted: "He (Whitaker) is not even posted in Iran anymore!"

One of those detained was identified by state TV as the husband of Austria's cultural attaché in Iran. Austrian officials were not immediately available to comment on the matter.

The TV also showed a picture of a third foreigner, identified as Maciej Walczak, a university professor in Poland, whom it said was visiting Iran as a tourist.

The TV report ran footage allegedly showing 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.

Reuters