Polling stations opened simultaneously at 9 a.m. (0430 GMT) throughout the country with the ingratiating vote of Seyed Ali Khamenei, the supreme leader of the Islamic republic.

Iranian supreme leader, Ayatollah Ali Khamenei, signs before casting vote in the presidential election June 17. (Xinhua/AFP)

    The voting is due to end at 7:00 p.m. (1430 GMT) but it can be extended until midnight if it is necessary, according to the order of the Interior Ministry in charge of the voting logistics.

    Some 46.7 million eligible voters, or all Iranians aged 15 and over, are expected to cast their ballots in some 42,000 stations in schools, mosques and prayer halls across the country.

    Fridays are the usual weekends in Iran, during which the always traffic-jammed Tehran will irregularly present a picture of less crowded streets and blue sky.

    Such a seldom picture is also witnessed in the morning of the voting day but interspersed with many police wagon and ambulances cruising back and forth in their precincts and patrolmen watching vigilantly the passersby around them.

Former president Akbar Hashemi Rafsanjani leaves a polling station after casting his ballot. (Reuters)

    The polling day came after 10 bombing explosions across the country which killed 10 people and injured scores of others in the past week.

    Tehran said the bombings were related to some foreign agents who attempted to spoil the atmosphere of the election and deterred Iranians from voting.

    Top Iranian officials, including Khamenei, have repeatedly urged the Iranians to go to vote regardless of the bombings and the opposition propaganda.

    Iran is expected to choose a powerful politician to lead the country out of its tough problems including the nuclear deadlock, the longtime hostility with the United States, the sluggish economy and high unemployment.

Leading reformist candidate Mostafa Moin casts his ballot. (AP)

    Seven candidates are running for the presidential post. They are former president Akbar Hashemi Rafsanjani, former Higher Education Minister Mostafa Moin, former police chief Mohammad Bagher Qalibaf, former parliamentary speaker Mahdi Karroubi, former state broadcasting body chief Ali Larijani, former Tehran Mayor Mahmoud Ahmadinejad and Vice President Mohsen Mehralizadeh.

    The first three have been viewed as the seeds according to recent polls.

    Mohsen Rezaei, former head of the Islamic Revolutionary Guards and a dragging conservative candidate, withdrew from the race at the last minute.

    Rafsanjani, though remaining front runner for months, is not guaranteed to succeed for his supporting rate has never reached 30 percent according to the polls.

    According to Iran's law, if nobody garners at least 50 percent of the votes, the top two vote-getters will have to go to a runoff held one week later, which means more uncertainties due to the reshuffled voters.