Cairo ? How do you count almost 40 million handwritten paper ballots in a matter of hours and declare a winner? That’s a key question in Iran’s disputed presidential election.

International polling experts and Iran analysts said the speed of the vote count, coupled with a lack of detailed election data normally released by officials, was fueling suspicion around President Mahmoud Ahmadinejad’s landslide victory.

Iran’s supreme leader endorsed the hard-line president’s re-election the morning after Friday’s vote, calling it a “divine assessment” and appearing to close the door on challenges from Iran’s reformist camp. But on Monday, after two days of rioting in the streets, he ordered an investigation into the allegations of fraud.