Tehran - Moderate former president Mohammad Khatami criticized the outcome of Iran's disputed election and called for the release of people arrested since the June 12 vote in a hard-hitting statement on Wednesday.

    Khatami was the third leading pro-reformer to publicly denounce the vote and its turbulent aftermath since Iran's top legislative body on Monday confirmed the victory of hardline President Mahmoud Ahmadinejad.

    Two defeated moderate candidates - former prime minister Mirhossein Mousavi and pro-reform cleric Mehdi Karoubi - both say the election was rigged in the incumbent's favor and have called for it to be annulled.

    Khatami, who was president from 1997 to 2005, supported Mousavi's presidency bid during the campaign.

    "Many people voted because we called for a high turnout. With this result and the way of confrontation (with post-election protests) you can be sure that even us (reformers) cannot ask people to take part in the next election," he said.

    "This is not in the interest of the establishment," he added.

    Reformist sources say scores of leading reformers have been detained in a crackdown since official election results released on June 13 sparked the gravest street unrest in Iran since the 1979 Islamic revolution.

    Riot police and religious Basij militia have suppressed huge demonstrations in which at least 20 people were killed.

    "If you want to calm the atmosphere, why are you carrying out mass arrests? Oppressing people will not help end the protests," Khatami said.

    Addressing the judiciary, he said: "If these people have committed crimes, why are their legal rights as citizens not preserved, why don't they have access to a lawyer, why are they not tried in a court, why haven't they been charged?"

    Khatami added: "Obtaining confessions in front of cameras is a useless old method ... confessions under pressure are not valid."

    Iran's police chief, Ismail Ahmadi-Moghaddam, earlier on Wednesday put the total number of detainees in the post-election unrest at 1,032 and said most had been freed.

    The rest had been "referred to the public and revolutionary courts in Tehran," Fars agency quoted him as saying.

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    (Reporting by Parisa Hafezi; writing by Fredrik Dahl; editing by Mark Trevelyan)