A Belgian court on Thursday sentenced an Iranian diplomat to 20 years in jail for plotting a bomb attack on an opposition rally in the most high-profile case of Tehran-backed terrorism in Europe since the 1979 revolution. Assadollah Assadi was convicted by a panel of three judges in Antwerp, Belgium, of planning and preparing the failed attack on a meeting of the National Council of Resistance of Iran in June 2018. The main target of the attack was believed to be Maryam Rajavi, the leader of the dissidents' group. A husband-and-wife team of bombers, Amir Saadouni and Nasimeh Naami, who were intercepted by Belgian police on the way to the rally on the outskirts of Paris were sentenced to 15 and 18 years in jail respectively. A fourth agent was sentenced to 17 years. The verdict was delivered amid tight security in Antwerp, where armed officers guarded the court and a police helicopter flew overhead. Visitors were subject to rigorous security checks with sniffer dogs and metal detectors. Assadi was not in court to hear the verdicts after refusing to appear at his trial and claiming that he should have been allowed diplomatic immunity. Assadi brought the explosives for the plot with him on a commercial flight to Austria from Iran. He then passed the bomb to a Belgian-Iranian couple at a Pizza Hut restaurant in Luxembourg, two days before the attack, while on a tour of castles with his family. The device contained 500 grammes of TATP that would have killed, the court heard. “To detonate this explosive at the conference would have caused deaths — because of the explosion and because of the chaos an explosion would have caused,” Luc Potargent, head of the panel of three judges said. Assadi gave the bombers instructions how to prepare, protect and transport the device. In a notebook found in his car, there were notes about attacks with other toxic materials. “By planning this attack, they have made Iranian refugees that tried to find a safe haven in Europe feel unsafe," the judge said. "A serious punishment is appropriate. It was an attack to their freedom of speech.” Assadi was arrested in Germany in the wake of the failed bombing and extradited after a court ruled that his immunity did not apply outside of Austria. The Belgian court said that Assadi, described as one of Iran’s most senior intelligence officials in Europe, did not have the right for immunity because he was not on diplomatic duty. “He was clearly going on vacation with his family,” said the judge. “The defendant is being accused of planning a potentially deadly attack and smuggling an explosive device from Iran under diplomatic cover. We can hardly consider he was performing diplomatic acts.” The target was the NCRI rally on June 30, 2018, attended by about 25,000 people including Rudy Giuliani, the former New York mayor and legal adviser to former US president Donald Trump. The botched attack was thought to have been approved at the highest levels in Tehran and the case has added new tension to relations between Iran and European governments. It comes at a sensitive time for Western relations with Iran as new US President Joe Biden is considering whether to lift sanctions on reimposed on the country by his predecessor Mr Trump and rejoin fellow world powers in the historic 2015 nuclear accord with Tehran. Iran has said that it will not accept the validity of any conviction having described the botched attack as a “false flag” operation by NCRI to lay blame on Iran, and a “complex trap”. It considers NCRI a terrorist group. Ms Rajavi called for the closure of Iranian embassies in Europe, the expulsion of its agents and the dismantling of its spying network. “If these measures are not taken, it means that the Iranian regime is paying no price for its crimes,” Ms Rajavi said. “It is the regime in its entirety which is being judged in this trial — it is about state terrorism.” Assadi — who was said to be running a Europe-wide spying network — warned authorities in March of possible retaliation by unidentified groups in the event of a guilty plea. Belgium’s state security officers said he worked for Department 312, the directorate for internal security, at the Ministry of Intelligence and Security, which is on the European Union’s list of organisations regarded as terrorist. One of the main responsibilities of MOIS is to conduct covert operations against the opposition abroad and to “identify and eliminate its members”, according to a 2012 report for US Congress. The verdicts raise fears of Iranian retaliation against dual-national prisoners held in the country, who have been used as bargaining chips in Tehran's broader battles. Here, The National profiles his plotters: <strong>Amir Saadouni — jailed for 15 years</strong> A former supporter — if not member — of the group he was sent to attack, Amir Saadouni, 40, was described as naive and easily manipulated by both his wife and Assadi. He says that he was the subject of a long-period of grooming by Iranian agents and only met Assadi in 2015 after approaches by two other people, he claimed. He confessed to his role in the plot when questioned by officers and claimed that the blast was not intended to hurt anyone — a claim dismissed by the Belgian court. Friends told The National after his arrest that he only claimed to be a dissident to prove that he was fleeing from oppression to secure Belgian citizenship. A friend who claimed to have known him for 15 years said that he was a kind man who worked in a shop and a port warehouse and enjoyed playing football and computer games. Saadouni told detectives that “due to all the stress”, he and his wife were getting divorced. <strong>Nasimeh Naami — jailed for 18 years</strong> Two stories emerged of Nasimeh Naami, 36, following her arrest. Friends said she worked a few nights a week in a shop and was a creature of routine. To investigators, she was a highly manipulative woman with closer links to Iran’s ministry of intelligence than she was letting on. She always travelled with her husband to meet Assadi and they received thousands of euros for their work from the spymaster — money they have now been told to pay back. The couple were said to have met online while she was still in Belgium and moved to Belgium where they lived together in a rented flat. She even manipulated her own husband by creating a fake identity online and pretending to be a woman from Iran called 'Negar' to flirt with her husband, talk to him about the plot and urge him to place the explosive inside the convention hall. <strong>Mehrdad Arefani — jailed for 17 years</strong> The Belgium-based Arefani promoted himself as a dissident poet and writer who claimed to have fled to Europe about two decades ago to avoid persecution. The 57 year old was on the fringes of the movement but was in reality the eyes and ears of Assadi for the Iranian operation. Spying equipment was found at his home in Brussels, including spectacles with a hidden camera and photographs of the offices of the dissident group the People’s Mujahedin Organisation of Iran, which was targeted in the plot. His role had been to guide the couple at the rally — but they never got there. He was well-paid for his work and police confiscated €226,000 ($270,500) that he had been paid by Assadi, the court was told. He was the only one of the four defendants to appear in court for the sentencing.