The European Union’s top diplomat confirmed on Tuesday that Johan Floderus, a Swedish diplomat working for the EU, has been held captive in Iran for more than 500 days.

Arriving at a meeting on development in the Spanish city of Cadiz, EU foreign policy chief Josep Borrell told reporters that Brussels was pushing “relentlessly” for the 33-year-old's release.

On Monday, Sweden partially confirmed a New York Times report on the detention, announcing that a Swedish citizen in his thirties had been held in Iran since April 2022.

But Borrell went further, confirming the prisoner’s name and that he works for the EU diplomatic corps.

“I want to say something about, if you allow me, a specific case, the case of Mr Floderus. He’s a Swedish citizen who worked for the European Union and has been detained illegally in Iran for the last 500 days,” Borrell said.

“I want to stress that I personally, all my team at all levels - European institutions in close coordination with the Swedish authorities, which have the first responsibility of consular protection - and with his family, have been pushing the Iranian authorities to release him.”

“Every time we had diplomatic meetings, at all levels, we have put the issue on the table. Relentlessly.”

“We have been working for the freedom of Mr Floderus and we will continue doing that in close contact with the family, respecting their will, and for sure with the Swedish government,” he said.

“This is very much in our agenda, in our heart and we will not stop until Floderus will be free.”

Iran announced in July last year it had arrested a man on suspicion of espionage, two weeks after an Iranian citizen received a life jail term in Sweden for his role in the Iranian regime’s 1988 mass executions of thousands of opponents.

A Stockholm court found former Iranian prison head Hamid Noury guilty of “aggravated crimes against international law” and “murder.”

Several capitals have accused Iran of practicing “hostage diplomacy” - arresting Western nationals to obtain concessions such as the release of detained Iranians.

In May, Belgian humanitarian worker Olivier Vandecasteele, 42, was released after 15 months in detention for alleged spying in a prisoner swap for Iranian diplomat Assadollah Assadi, sentenced to 20 years for plotting to bomb an opposition rally in Paris.