Iran has broadcast what it described as details of the arrest of two French citizens earlier this month — calling them "spies" who had sought to stir up unrest.
The country's intelligence ministry on May 11 said it arrested two Europeans, accused of stirring up insecurity in Iran. Officials did not reveal their nationalities.
France has condemned their detention as baseless and demanded their immediate release, Reuters reported.
On Tuesday, Iranian state television named the two as Cecile Kohler, 37, and her partner Jacques Paris, 69.
It said "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 Washington, US State Department spokesman Ned Price called for their immediate release.
In recent months, Iranian teachers across the country have staged protests demanding better wages and working conditions, state media reports show. 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," state TV said, showing Ms Kohler and Mr Paris apparently talking in a meeting with people who it said were protesting Iranian teachers.
The detentions come at a sensitive time, as the US and parties to Iran's 2015 nuclear deal struggle to restore the pact that was abandoned in 2018 by then US president Donald Trump.
US State Department on nuclear deal: 'The ball is in Iran's court'
The TV footage showed what it said was their arrival from Turkey at Tehran's International Imam Khomeini Airport on April 28, 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 last week on Thursday that he suspected that one of his staffers and her husband were missing on a holiday in Iran.
Two other French citizens are being 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 citizen was also detained in Iran.
