At least eight European passport holders are still being held in Iran, after a prisoner swap that saw two Swedes freed on Saturday.

Johan Floderus, 33, a European Union diplomat, and Saeed Azizi were released in exchange for former Iranian prisons official Hamid Noury, 63, who was serving a life sentence in Sweden over the killing of thousands of prisoners in Iran in the late 1980s.

Human rights groups say those still in custody are being kept by Iran for use as bargaining chips in negotiations with foreign governments.

Here are the known prisoners:

  Britain 

 British-Iranian labour rights activist Mehran Raoof was arrested in October 2020 on national security charges and sentenced to 10 years and eight months in jail, according to Amnesty International.

He was held for months in solitary confinement in Tehran's notorious Evin prison, where he managed to smuggle out a letter last year complaining of harsh treatment of dual nationals, Amnesty said.

 Germany 

 German-Iranian Nahid Taghavi, in her late 60s, was sentenced to 10 years and eight months in jail in August 2021 for "anti-regime propaganda" and "membership of an illegal group". She was arrested at her Tehran apartment in October 2020, and she too is being held in Evin prison.

Jamshid Sharmahd, a German citizen of Iranian descent, was captured by Iranian authorities in August 2020 while travelling through the UAE, according to his family.

He was sentenced to death in February 2023 after being charged with terrorism over the 2008 bombing of a mosque that killed 14 people. His family have dismissed the accusations, but fear he could be executed any day.

 France 

 French teachers' union official Cecile Kohler and her partner, Jacques Paris, were detained in May 2022 while sightseeing in Iran. They are accused of spying.

Another French citizen, identified only by his first name, Olivier, has been in detention since October 2022. French authorities have not released details of his case.

 Austria 

 An Austrian national, who has not been named, was sentenced to seven and a half years in jail in Iran last year for spying, says Vienna.

 Sweden 

 Iranian academic Ahmadreza Djalali, a resident of Sweden, was arrested during a visit to Iran in April 2016 and sentenced to death in 2017 on charges of spying for Israel's Mossad.

He was granted Swedish citizenship while in jail. His hanging was postponed but his family says he remains on death row.

The Swedish foreign ministry has also confirmed that Iran is holding another Swedish man, who is in his twenties and was arrested in January.

Swedish media reported however that this man was the target of an international arrest warrant in connection with a deadly shootout in Sweden.