Islamic Revolutionary Guard Corps IRGC (Sepah Pasdaran)
Founded by Ayatollah Khomeini after the 1979 revolution. Its commander, Major General Mohammad Ali Jaafari, reports directly to the supreme leader, Ayatollah Ali Khamenei. IRGC officers wear dark-green uniforms with emblems showing a fist clutching an automatic rifle. Unwilling in the past to be used for internal security duties. This is likely to remain true today partly because of the influence of Mohsen Rezaei, its wartime commander and one of the three presidential candidates.
Basij ("Mobilisation") Force
All-volunteer militia of about one million involved in crushing protests over the past three days. The shooting in Tehran's Azadi Square on Monday arose from a clash between Basiji and pro-Mousavi demonstrators. Basiji generally wear plain clothes, are thuggish-looking and carry wooden sticks and iron bars. They have powers of arrest. They have a local organisation in almost every city in Iran. Have undergone a revival under Ahmadinejad. Professor Ali Ansari of the University of St Andrews said: "The regime will use the Basij to create a sense of emergency on the streets and then send the police in. That's why discipline is important for Mousavi's supporters."
Controlled by the interior ministry, run by pro-Ahmadinejad loyalist Sadeq Mahsuli. Unit 110 specialises in rapid-response activities in urban areas and dispersing gatherings. Black-clad special forces anti-riot teams have been seen operating on motorbikes in central Tehran. Plain-clothes police were reportedly involved with Basij in an attack on students at Tehran University.
Ministry of intelligence services (MOIS)
One of the most powerful ministries. Has traditionally operated under the guidance of the supreme leader. Oversees secret police, charged with maintaining the security of the regime and counter-espionage. Plays a role in monitoring Iranian media and foreign journalists through the ministry of Islamic guidance. Intelligence minister Gholamhossein Mohseni-Ejei said yesterday his ministry was seeking two types of people over the current unrest. "One wanted to achieve its goal through explosions and terror. The second was made up of counter-revolutionary groups who penetrated the headquarters of the election candidates."
Not normally employed on internal security duties. Personnel totalling 945,000 in all three service branches but it is overshadowed by the parallel and rival IRGC.