Iranians are voting Friday to elect 290 members of parliament and 88 members of the Assembly of Experts, a panel of clerics responsible for appointing and monitoring Iran's supreme leader.

Key figures and voting procedures of this twin vote:

- Number of voters: 54,915,024 are eligible to cast ballots, 8,475,077 of them in Tehran province, according to the interior ministry. Iran's population is around 79 million.

A total of one million people will be mobilised to organise and run the elections, and around 250,000 policemen will be on duty.

In each polling station, apart from representatives of the interior ministry and the Guardian Council, a constitutional watchdog, officials of other state bodies, including the police, will also be present.

Candidates may have observers in polling stations.

- The interior ministry is responsible for organising the elections, while the Guardian Council (made up of six clerics appointed by the supreme leader and six jurists recommended by the judiciary) is responsible for supervising the polls.

- Number of parliamentary candidates: 6,229, including 586 women, were approved by the Guardian Council -- 51 percent of the approximately 12,000 who initially registered to run.

- For the Assembly of Experts, the Guardian Council approved 161 candidates to contest the 88 seats of the chamber, out of 800 who applied. Members are elected by single majority vote.

- Two-round legislative vote: Successful candidates are elected in the first round if they obtain over 25 percent of votes cast. For each seat left empty, two runner-ups will compete in a second round, likely within two or three weeks.

- In Tehran, voters elect 30 parliamentarians. In other cities, the number of MPs varies according to the population. Electors must write the full names of candidates they support on the ballot paper. In the capital, this means voters should write the names of 30 candidates on the ballot for parliament and 16 candidates for the Assembly of Experts, though many do not use their full allowance.

The painstaking procedure makes the voting process complex and the counting protracted.

- The list of candidates in polling stations is displayed in alphabetical order. The location is often a school, mosque or state building where men and women vote separately. Voters are not registered and they can vote in any constituency. The only restriction is that the voter cannot change constituency between the two rounds of voting. Voters must present two identity documents, the national ID card and an Iranian document resembling a passport called Shenasnameh, which is stamped in each election, making it impossible to vote multiple times.

- The results of small constituencies will be announced on Friday night, and those in provincial cities are likely on Saturday. But results will take three days in Tehran. Official final results will be announced by the interior ministry, and must be approved by the Guardian Council who can annul the vote in some constituencies.