Two French citizens detained in Iran on spurious spying charges have been released and are on their way back to France.

President Emmanuel Macron announced the news on Friday that Bernard Phelan and Benjamin Brière were free, the two men among unknown numbers of diplomatic hostages held by the regime. "We will continue to work towards the return of those of our fellow nationals who are still detained in Iran," Macron said in a tweet.

French Foreign Minister Catherine Colonna spoke to her Iranian counterpart Hossein Amir Abdollahian, a few hours earlier.

Ties between France and Iran have deteriorated in recent months. Tehran had detained seven French nationals in what Paris described as arbitrary arrests equivalent to state hostage-taking.

The statements were released a day after the twitter account of Iran’s embassy in Dublin announced the release of Franco-Irish citizen Bernard Phelan who was earlier sentenced to 6.5 years in prison for "providing information to another country."

Benjamin Brière was sentenced to eight years in prison on spying charges. He had been held in Iran since May 2020, when he was arrested after flying a remote-controlled mini helicopter used to obtain aerial or motion images near the Turkmenistan-Iran border.

Philippe Valent, his France-based lawyer, called the espionage charges against his client a "fiction" and his trial "a parody staged by the Revolutionary Guard".

In the past decade, Iran's Revolutionary Guard have arrested dozens of dual nationals and foreigners, mostly on unproven allegations of espionage and breach of security, in what human rights organizations have said is essentially hostage taking.

Iran has been accused of wrongfully detaining at least a dozen foreign and dual nationals on trumped up charges, effectively as hostages to extract concessions from Western governments. However the full extent of these prisoners is unknown.