Iran's state television on Tuesday showed what it described as details of the arrest of two French citizens earlier this month, saying they were spies who had sought to stir up unrest.

Iran's intelligence ministry had said on May 11 it had arrested two Europeans for allegedly fomenting "insecurity" in Iran, but had not revealed their nationalities.

France has condemned their detention as baseless and demanded their immediate release, in an incident likely to complicate ties between the countries as wider talks on reviving a nuclear deal stall.

On Tuesday, state television named the two as Cecile Kohler, 37, and her partner Jacques Paris, 69, adding that "the two spies intended to foment unrest in Iran by organising trade union protests". Iran's judiciary has yet to comment on the matter.

In Paris, there was no immediate response from the French Foreign Ministry to a request for comment on Iranian television's assertions.

In recent months, Iranian teachers across the country have staged protested demanding better wages and working conditions, according to Iranian state media. Dozens of them have been arrested.

"They travelled to Iran as tourists ... But they took part in anti-government protests and met members of the so-called Teachers' Association," it said, showing Kohler and Paris apparently talking in a meeting with what it said were protesting Iranian teachers.

The TV footage showed what it said was their arrival at Tehran's International Imam Khomeini Airport on April 28 with Turkish Airlines from Turkey, as well as their arrest on their way to the airport on May 7.

Christophe Lalande, federal secretary of France's FNEC FP-FO education union, told Reuters on May 12 he suspected that one of his staffers and her husband were missing on a holiday in Iran.

Two other French nationals are held in Iran on national security charges their lawyers say are politically motivated.

Rights groups have accused Iran of trying to extract concessions from other countries through such arrests. Iran has repeatedly dismissed the charge.

Western powers have long demanded that Tehran free their citizens, who they say are political prisoners.

The two French citizens were arrested a week after a Swedish national was also detained in Iran. The detentions come at a sensitive time, as the United States and parties to Iran's 2015 nuclear deal struggle to restore the pact that was abandoned in 2018 by then-U.S. President Donald Trump.

(Writing by Parisa Hafezi; Editing by Bill Maclean and Jon Boyle)