France said on Thursday that two of its citizens have been arrested in Iran and demanded they be freed immediately.
"The French government condemns this baseless arrest. It calls for the immediate release of these two French nationals," the foreign ministry said in a statement.
Iran's intelligence ministry had said on Wednesday that it had arrested two Europeans for allegedly fomenting "insecurity" there, but it had not revealed their nationalities.
Christophe Lalande, federal secretary of France's FNEC FP-FO education union, told Reuters earlier that he suspected that one of his staffers and her husband, missing on a holiday in Iran, were the two arrested.
While there was no "absolute certainty", there was a "strong presumption" that she has been arrested, Lalande said of his colleague, adding that she had been due back in France earlier this week.
The two arrested were accused of "organizing chaos and social disorder aimed at destabilizing (Iran)" in conjunction with foreign intelligence services, Iranian state TV on Wednesday cited Iran's intelligence ministry as saying.