Iran's Revolutionary Guards arrested several foreign diplomats, including a Briton, accusing them of "spying," the Fars news agency and state television said Wednesday, AFP reported.
But the British government quickly denied that any of its personnel had been arrested, describing the reports as "completely false."
Iranian state television reported that the Briton, identified as Giles Whitaker, the UK government's deputy head of mission in Iran, was only expelled from "the area" where the diplomats had been arrested in central Iran.
State television accused him of "carrying out intelligence operations" in military areas.
Video showed images of a man presented as Whitaker speaking in a room.
A state TV journalist said the diplomat "was among those who went to the Shahdad desert with his family as tourists," referring to an area in central Iran.
"As the images show, this person took photos... in a prohibited area where at the same time a military exercise was taking place," the broadcaster said.
Britain's government categorically denied the reports.
The number, nationality and date of arrest of the other diplomats detained was not immediately clear.
But Iranian state television said that "apparently Israel wants to open a file on the possible military dimension of Iran's nuclear program, using nationals from third countries who are linked to foreign embassies," it charged.
State television also showed images of a man it identified as "Maciej Walczak, head of the microbiology department at the Nicolaus Copernicus University in Poland."
Walczak, whose nationality was not specified, "entered Iran with three other people in the context of scientific exchanges but he went to the desert region of Shahdad as a tourist while missile tests were being carried out," state television said.
It said he took rock and soil samples.
Fars meanwhile said those arrested took rock samples in the desert for "espionage" purposes.
State television presented another man, identified as "Ronald, the spouse of the Austrian embassy's cultural adviser," who it said went to a village in the Damghan area east of Tehran and "took rock samples."
He was also accused of "filming a military area in Tehran," the broadcaster said.