Iran's judiciary confirmed on Wednesday a death sentence for a German-Iranian national over a deadly mosque bombing in 2008, a decision Berlin described as "unacceptable".
"Jamshid Sharmahd's sentence has been upheld by the Supreme Court," judiciary spokesman Massoud Setayeshi told reporters in Tehran, saying "measures" ahead of the 68-year-old's execution "will be taken later".
German Foreign Minister Annalena Baerbock said the decision was "unacceptable" and Sharmahd had "never had anything like a fair trial".
"We call on Iran to reverse this arbitrary sentence immediately," she wrote on Twitter.
Germany's ambassador to Iran has cut short a business trip and is on his way back to Tehran, she added.
A foreign ministry spokesman earlier said Germany was "dismayed" by reports of the decision, adding that if they were true the situation was "extremely serious".
The Tehran Revolutionary Court in February sentenced Sharmahd to death after he was convicted of involvement in the April 2008 attack in the southern city of Shiraz that killed 14 people.
Germany has condemned the sentence and declared two staff members at Iran's embassy in Berlin personae non gratae, ordering them to leave the country.
Tehran, in turn, expelled two German diplomats last month.
Prosecutors had also accused Sharmahd, a US resident, of having established contact with "FBI and CIA officers" and of having "attempted to contact Israeli Mossad agents".
Iranian authorities announced in August 2020 Sharmahd had been apprehended in what they described as a "complex operation", providing no specific details of the arrest.
His family says he was kidnapped by the Iranian security services while in transit in Dubai and then brought to Iran.
At least 16 Western passport-holders, including six French, are being held in Iran on various charges. Most hold dual nationality, which Iran does not recognise.
Three dual nationals including Sharmahd have been sentenced to death or executed over security-related charges since the start of the year, according to the judiciary.
The execution in January of Alireza Akbari, a former Iranian official with British citizenship convicted of espionage, has provoked international outcry.