Sweden's foreign minister said on Saturday the trial of a Swedish EU diplomat, held captive for over 600 days in Iran, had begun in Tehran.
"I have been informed today that the trial of Johan Floderus has started in Tehran," foreign minister Tobias Billstrom said in a written statement to AFP.
Johan Floderus, 33, was arrested on April 17, 2022, at Tehran airport as he was returning home from a trip with friends.
The Swede, who works for the European Union diplomatic service, is being held in Tehran's notorious Evin prison.
Billstrom said Floderus had been "arbitrarily detained".
"There is no basis whatsoever for keeping Johan Floderus in detention, let alone bringing him to trial.
"Both Sweden and the EU have made this very clear to representatives of Iran," Billstrom said.
In September, Iran's judiciary said that Floderus had "committed crimes" in the country and an investigation into his case was being finalised.
An EU official, speaking on condition of anonymity, told AFP in September that they had not received "a clear answer" as to why Floderus had been detained.
Iran has long used detained foreign nationals as bargaining chips to secure the release of its citizens or frozen funds held abroad.
Floderus's arrest came 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.
EU relations with Iran have also been battered by Tehran's deliveries of weaponry to Russia and a crackdown on protests over the death of Mahsa Amini. The young Iranian Kurdish woman died on September 16, 2022, while being held by Iran's religious police for allegedly breaching the Islamic republic's strict dress code for women.
The 27-nation EU has placed repeated rounds of sanctions on Iran over the weapons supplies and the repression of demonstrators.