Iran has a complex political system comprising elected and un-elected institutions, but with overall power clearly in the hands of the supreme leader.
In the wake of Friday's disputed presidential election, here are some facts on Iran's key institutions.
- Ayatollah Ali Khamenei succeeded the founder of the Islamic republic, Ayatollah Ruhollah Khomeini, upon his death in June 1989.
- The supreme guide is appointed for life and has the final word on all matters of state.
- Khamenei has praised Ahmadinejad's re-election.
- He names the head of the judiciary, six members of the powerful Guardians Council, the commanders of the armed forces and confirms the election of the president.
- The president is elected by the people to a four-year term. He heads the government but has no control over key institutions such as the courts and the armed forces.
- Mahmoud Ahmadinejad won a landslide victory for a second mandate in the June 12 election, according to official figures.
- A 12-member body which has the authority to interpret the constitution, and approve or veto bills passed by parliament.
- It has the power to screen candidates wishing to stand in presidential, parliamentary or Assembly of Experts elections.
- Iran's defeated presidential candidate Mir Hossein Mousavi said on Sunday he has asked the Guardians Council to cancel the result of Friday's poll.
- Six members are clerics appointed by the supreme leader while the other six are jurists named by the head of the judiciary (who is also selected by the supreme leader) and approved by parliament.
- Iran's top political arbitration body tasked with resolving disputes between parliament and the Guardians Council. It also acts as an advisory council to the supreme leader.
- Known as the Majlis, it is elected by popular vote every four years and has 290 seats.
- All bills passed by the parliament must be approved by the Guardians Council.
Assembly of experts
- An 86-member body which selects the supreme leader and supervises his activities. It meets every six months.
- Members are elected by public vote, although candidates are selected by and subject to the approval of the Guardians Council.
Revolutionary Guard Corporation
- Set up in the wake of the 1979 revolution to defend the Islamic republic from 'internal and external threats' the Guards are considered Iran's ideological army.
- The Guards are under the direct command of the supreme leader, who also appoints their commanders.
- The force -known in Farsi as Sepah-eh Pasdaran- is believed to be 120 200 strong.
- The Guards work in parallel with the regular armed forces but have their own land, sea, air and missile unit. They play a key role in policing Iran's borders.
- They are also tasked with fighting armed opposition groups through the Basij Islamist militia, which has around 12 million volunteers who receive training at 11 200 centers across the country.
- Iran's opponents say the Guards were responsible for creating the Shiite militant group Hezbollah in Lebanon.
Supreme National Security Council
- Iran's top national security decision-making body, specifically responsible for nuclear negotiations with the West.
- It is comprised of key ministers such as intelligence, defense, interior and the various heads of armed forces.
- The head of the judiciary, currently Ayatollah Mahmoud Hashemi Shahroudi, is appointed by the supreme leader.
- There is also a Supreme Court, which must approve death penalties, as well as Revolutionary Courts, which handle national security-related offences.
- The force is estimated to number 523,200.