The family of a Belgian aid worker being held in Iran have demanded their government does “everything necessary” to secure his release.
Olivier Vandecasteele, 41, was arrested in Iran at the end of February and is being held in Tehran's Evin prison on “espionage” charges.
“Even though he's innocent, he has been rotting away for nearly five months in total solitary confinement,” his sister Nathalie Vandercasteele said.
“Today Olivier needs your support … It is unthinkable for our family that our democratic Belgium isn't doing everything necessary to get innocent prisoners out of countries like Iran.”
Mr Vandecasteele’s family and rights groups including Amnesty International say the case is an example of Iran's tactic of taking foreigners hostage to pressure western countries to make concessions.
Mr Vandercasteele's mother Annie barely held back tears as she implored authorities to help her son.
“Since he finished his studies, he has been far from us to help others. Now, help us to get him out of there and bring him home so we can hug him close,” she said.
Nathalie Vandercasteele said her brother had received two consular visits that revealed he has suffered major weight loss and a foot infection.
“He has spent two months without even a mattress, in a cell lit up around the clock, and is being subjected to daily psychological pressure from interrogators,” she said.
They believe Iran is seeking to force Belgium to release one of its diplomats who was last year found guilty of masterminding a 2018 foiled bomb attack outside Paris.
Assadollah Assadi, 50, is serving a 20-year sentence in a Belgian prison for attempted “terrorist” murder and “participating in the activities of a terrorist group”.
Belgium's government is currently urging parliament to approve a controversial prisoner-swap treaty with Iran.
Assadi was attached to Iran's embassy in Austria where investigators said he served as a regime agent under diplomatic cover.
After European intelligence services uncovered a plot to set off a bomb at a rally of Iranian dissidents outside Paris, Assadi, who supplied the explosives, was arrested in Germany, where his claim for diplomatic immunity was denied.
He was extradited to Belgium for his trial, and chose not to challenge his sentence on appeal.
Tehran has strongly denied the charges levelled at the diplomat.