Belgium's constitutional court on Thursday suspended a prisoner exchange treaty with Iran, which has been criticised for opening the way for a bomb-plot mastermind to return to Tehran.
Opponents of the Iranian government challenged the deal, which they said was "tailor-made" to permit the release of Assadollah Assadi, an Iranian diplomat sentenced last year to 20 years in prison.
An Antwerp court convicted him of supplying explosives for a foiled 2018 bomb plot against a meeting outside Paris of Iran's exiled opposition.
The Belgian government has said the treaty is the only way to secure the release of aid worker Olivier Vandecasteele, who was detained in Iran in February.
The constitutional court ruled that the treaty was "suspended" pending a final ruling within the next three months.
"There is for the moment no longer any legal basis allowing this transfer," Francois Tulkens, a lawyer acting for the opposition group the National Council of Resistance of Iran, told AFP.
Protests in Iran continue - in pictures
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Iranians protest in Tehran after the death of 22-year-old Mahsa Amini after she was detained by the morality police in September. AP Photo -
Protests have intensified despite a vicious government crackdown that has left as many as 200 people dead, although estimates of the toll by rights groups vary. AP Photo -
At least eight members of the security forces have also been killed or wounded during the unrest and there are signs that violent resistance could be intensifying. AP Photo -
A fire burns at the office of the governor of Mahabad, in the West Azerbaijan province of Iran. AFP -
Protesters gather in the a courtyard of Chitgar complex in western Tehran. AFP -
Iranian protesters continue to defy a deadly crackdown by security forces. AFP -
A woman cuts her hair at the grave site of Nika Shahkarami in the city of Khorramabad, during a reported memorial held to mark 40 days since the death of the 16-year-old. AFP -
A woman not wearing a headscarf stands on top of a vehicle as thousands make their way towards Saqez, Mahsa Amini's home town, to mark 40 days since her death in police custody. AFP -
Iranian riot police prepare to confront protesters the capital, Tehran. AFP -
Iranian protesters surge forward amid clashes with riot police in Tehran. AFP -
A crowd blocks an intersection during a protest to mark 40 days since Amini's death in custody. AP Photo -
Iranian police arrive to disperse a protest in Tehran. AP Photo -
Protesters chant at a vigil for Amini at the Khajeh Nasir Toosi University of Technology in Tehran. Reuters -
Students at Sharif University of Technology attend a protest. AP Photo -
Police outside Sharif University during a student protest. AP Photo -
Students at the university protest over the death of Amini, who was in 'morality police' custody for allegedly breaking strict rules on head coverings for women. AP Photo -
The students' banner says: 'No to mandatory hijab'. AP Photo
The Assadi case sparked a furious reaction in Iran.
The Antwerp court ruled that he had masterminded the bomb plot under diplomatic cover as an envoy to Austria, and thus had no immunity in Belgium.
Tehran has demanded that Belgium recognise Assadi's diplomatic status and release him.
Iran's plots against foreign officials and dissidents — in pictures
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Relatives carry the body of Hassan Al Qahtani outside the Grand Mosque in Riyadh in May 2011. The Saudi diplomat was shot dead in Karachi by a man believed to have been linked to Iran's Islamic Revolutionary Guard Corps' Quds Force. Reuters -
Iran has been attempting to kill or capture former US president Donald Trump after he ordered the air strike that killed the IRGC's Quds Force commander, Qassem Suleimani, in January 2020. AP -
Former secretary of state Mike Pompeo is believed to have been Iran's second target, after former national security adviser John Bolton, marked for assassination. AP -
Gen Kenneth McKenzie, former commander of the US Central Command, has been high on Iran's list of people to be killed in retribution following Suleimani's death. AFP -
Abdul Rahman Ghassemlou, secretary general of the Democratic Party of Iranian Kurdistan, was shot dead in July 1989 by suspected Iranian agents in Vienna. Getty -
Shapour Bakhtiar, the last Iranian prime minister under the Shah, was killed at his home in August 1991 by assassins believed to have been sent by Tehran. AFP -
Iranian poet and entertainer Fereydoun Farrokhzad's death has never been solved but German police believe he was killed by Iranian operatives.
Mr Vandecasteele, 41, began a hunger strike over the "inhuman" treatment by his captors in Iran, his family said last week, expressing worries about his failing health.
He is one of several western nationals detained in Iran, in what foreign-based activists have said is a bid to extract concessions. Most of them also hold Iranian passports.
