UN rights experts have condemned Iran’s “arbitrary” detention of Belgian aid worker Olivier Vandecasteele and demanded his immediate release. “We believe Mr. Vandecasteele has been arbitrarily deprived of his liberty and is a victim of enforced disappearance for periods of detention,” the independent UN human rights experts said in a statement. “His right to a fair trial before an independent and impartial tribunal has been violated. These are flagrant violations of Iran’s obligations under international law,” they said. Vandecasteele, 40, was arrested on February 24, 2022. In their statement, the UN experts declared that he had suffered ill-treatment in detention and that his health condition was critical. Vandecasteele had been sentenced to 40 years of imprisonment and 74 lashes on charges of espionage against Iran, cooperating with the US, currency smuggling, and money laundering. Under Iranian law, Vandecasteele is eligible for appeal after 12 years and six months. “We are gravely concerned over the mental and physical health of Mr. Vandecasteele,” the experts said. “Mr. Vandecasteele requires special attention and medication.”  Belgian-Iranian ties have been tense since the arrest of Iranian diplomat Asadollah Asadi who was sentenced to 20 years in prison in Belgium over plots to stage a “terrorist” attack against the Iranian opposition. The statement urged Iran to release the many foreign and dual national citizens who remain arbitrarily detained in Iran and condemned the execution on January 14 of the British-Iranian, Alireza Akbari. Moreover, France is extremely worried about the health of Bernard Phelan, a French-Irish citizen held in Iran since October 2022, who relatives say is on hunger strike, the foreign ministry said on Tuesday. Local media reported that a German national was also arrested. "He is showing serious signs of physical and psychological exhaustion," said a French diplomatic source, adding he was in a "critical state." The Iranian authorities have so far refused to release Phelan on medical grounds despite repeated requests from the French and Irish authorities, the source said. The French Foreign Ministry said Phelan was one of seven French nationals currently held arbitrarily by Iran, and Paris was “extremely worried about his health, which is poor and requires appropriate medical monitoring, which is not ensured in detention”. Phelan’s sister, Caroline Masse-Phelan, told AFP her brother had started a dry hunger strike on Monday, refusing water, in addition to the food hunger strike he had been on since the start of the year. “We are stepping up the pressure on Iran, in coordination with the Irish government, to ensure that our compatriot is released without delay,” the French foreign ministry said. Tehran is accused of using western nationals to put pressure on the West.