Iran's Revolutionary Guards detained several foreigners, state media reported on Wednesday, including the UK's second most senior diplomat in the country. 

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

Footage played on television showed the deputy head of mission at the British Embassy, Giles Whitaker, and his family in central Iran. Whitaker appears to be collecting soil samples in the video.

The UK Foreign Office denied that its diplomat was arrested, calling the report "completely false."

Other detainees included the husband of Austria's cultural attache in Iran and Polish university professor Maciej Walczak The professor, along with three colleagues, was in Iran on a scientific exchange program. There was also footage purporting to show Walczak taking pieces of soil from the ground.

Iranian media said their alleged sample collection 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. A Belgian humanitarian worker, as well as a French couple who were sightseeing in Iran have all been detained in recent months for alleged spying or "agitating."

The detentions follow rising tensions over the rapid advancement of Iran's nuclear work, while talks to revive the landmark 2015 nuclear agreement have stalled.

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. Although Tehran denies this, British-Iranian journalist Nazanin Zaghari-Ratcliffe was released after six years in prison in late March, immediately after the UK paid hundreds of millions of pounds that Tehran claimed it had owed them for decades.

es/sms (AFP, Reuters)