Belgium's Foreign Affairs Ministry summoned Iran's ambassador on Tuesday after a Belgian aid worker was sentenced to 40 years in an Iranian prison and 74 lashes for alleged spying, money laundering and currency smuggling.
Olivier Vandecasteele, 41, was handed sentences totalling 40 years on a range of charges, but as they run concurrently he will serve 12 and a half years in jail, the judiciary's Mizan Online website reported.
Iran arrested Vandecasteele in February 2022, and he has since been held in conditions that Belgium's government has described as "inhumane".
He was found guilty of "espionage against the Islamic Republic of Iran for the benefit of foreign intelligence services", and given a 12-and-a-half year sentence.
He was given the same sentence for "co-operation with the hostile government of the United States".
Vandecasteele received the same sentence for "money laundering", and another two and half years and 74 lashes for "professional currency smuggling to the amount of $500,000".
He can appeal against the verdict, the website said.
"No information regarding the charges or the verdict has ever been officially provided by Iran," Belgian Foreign Minister Hadja Lahbib said on Twitter.
Supporters of Vandescasteele and rights groups contend that he is being held as part of Iran's "hostage diplomacy", an effort by Tehran to have Belgium release an Iranian diplomat jailed for terrorism.
Assadollah Assadi was found in guilty in 2021 of orchestrating a plot to blow up an event organised by an exiled Iranian opposition group outside Paris in 2018.
The plot was foiled by European intelligence services, and Assadi, a diplomat stationed in Austria who was identified as having provided the explosives for the bomb, was sentenced to 20 years in prison.
Vandecasteele's family in mid-December announced that, according to the information they had, he had been sentenced to 28 years in an Iranian prison on unknown charges.
Days later, Belgium urged its citizens — including Iranians holding Belgian passports — to leave Iran because of the risk they could be "arbitrarily detained" in the same way.
In July last year, Belgium and Iran signed a prisoner-swap treaty that Brussels regarded as a path to securing Vandecasteele's release.
But Belgium's Constitutional Court suspended the treaty after exiled Iranian opposition members challenged it on the grounds it would lead to the release of Assadi.
The constitutional court said the suspension was in place pending a ruling on the legality of the treaty.