Staff representatives have accused the airline, due to resume flights to the Iranian capital later this month, of forcing female staff to wear clothing that is an “ostentatious religious sign” which goes against French law, according to The Guardian.

Union leaders said the dress code was an attack on personal freedoms and insisted the measure had to be voluntary, while Air France believes the rules were not new and already applied to cabin crew during stop-overs in Saudi Arabia, where hostesses were required to wear an abaya covering their body.

The Airline well begin three daily services to the Iranian capital on April 17, eight years after they were stopped following the imposition of international sanctions against Tehran – which were lifted in January after Iran agreed to dismantle its nuclear programme.

Christophe Pillet, of the SNPNC union and a member of the Air France staff committee, said the instructions had sparked widespread concern, telling AFP: “Every day we have calls from worried female cabin crew who say they do not want to wear the headscarf.”

He said airline management had also raised the possibility of penalties against staff who refused to follow the dress code.

Françoise Redolfi, another union leader, told French public radio station, “They are forcing us to wear an ostentatious religious symbol. We have to let the girls choose what they want to wear. Those that don’t want to must be able to say they don’t want to work on those flights.”

She added: “Many female members of flight crews have told us that it’s out of the question they be obliged to wear headscarves. It’s not professional and they see it as an insult to their dignity.”

In a statement, Air France said: “Iranian law requires the wearing of a veil covering the hair in public places for all women present on its territory. This obligation is not required during the flight and is respected by all international airlines serving the Iranian Republic.”