Iran on Tuesday resumed the mass trial of opposition activists and protesters charged with rioting and plotting to topple the ruling Islamic system through a "velvet revolution" following the country's disputed presidential election. The proceedings in Teheran's Revolutionary Court are seen as an attempt by the authorities to deliver a final blow to the pro-reform movement and discredit the anti-government protests that have persisted since the June 12 vote. Hundreds of protesters, opposition politicians and activists have been arrested in the crackdown on the opposition, which has denounced President Mahmoud Ahmadinejad's proclaimed election victory. Tuesday's hearing was the fourth so far in the extraordinary trial that started last month. Iran's official IRNA news agency said there were new defendants in the courtroom on Tuesday. They included former Deputy Interior Minister Mostafa Tajzadeh, former Deputy Foreign Minister Mohsen Aminzadeh and former government spokesman Abdollah Ramezanzadeh - all prominent reformists. Also among those in the court was senior reformist Saeed Hajjarian, a former city councilor and a close aide to former reformist president Mohammad Khatami. Hajjarian, gravely wounded in an assassination attempt in 2000 when he was shot in the head from close range, has been forced to use a wheelchair and has difficulties speaking. His arrest and trial have drawn wide condemnation, even from conservatives within the ruling system. Hajjarian was considered the engineer behind Khatami's democratic reform program and also served as a top intelligence official, often described as the "walking memory" of recent Iranian history because of his access to classified information and the Islamic establishment's secrets. Hundreds of thousands of Iranians have marched in days of street protests after the June 12 election, claiming the official results were rigged in Ahmadinejad's favor and that pro-reform challenger Mir Hossein Mousavi was the true winner. Authorities have unsuccessfully tried to portray the protests as riots incited by foreign powers and not fueled by internal dissent. The defendants are charged with fomented riots and attempting to overthrow the ruling system with a "velvet revolution," similar to uprisings in Eastern Europe. The phrase comes from the peaceful 1989 Velvet Revolution that overthrew decades of communism in Czechoslovakia. The indictment also says that Mousavi's campaign was instigated by the "British propaganda" machine. Britain has denied any interference in Iran's elections.