Massive turnout in Iranian election

At stake is re-election for hard-line President Mahmoud Ahmadinejad or his replacement by reformer Mir Hossein Mousavi who favours greater freedoms and improved ties with the West.

Crowds formed quickly at many voting sites in areas considered strongholds for both candidates in the Islamic republic.

Mr Mousavi, who served as prime minister in the 1980s, has become the surprise hero of a powerful youth-driven movement.

The turnout was massive - with some officials predicting a record-breaking surge to the polls - and voting was extended by one hour.

There were no reports of unrest, but a top Mousavi aide said some polling stations in north-western and southern provinces ran out of ballots, which he claimed was a "deliberate attempt by the government to keep people from voting".

The fiery, month-long campaign unleashed passions which are likely to bring a record turnout. The mass rallies, polished campaign slogans, clever internet use and televised debates more closely resembled Western elections than the scripted campaigns in most other Middle Eastern countries.

In a sign of the bitterness of the campaign, the Interior Ministry, which oversees voting, said all rallies or political gatherings would be banned until after all results are announced, which is likely to be on Saturday.

The outcome will not sharply alter Iran's main policies or sway high-level decisions as those crucial policies are all directly controlled by the ruling clerics headed by the unelected Supreme Leader Ayatollah Ali Khamenei.

But Mr Mousavi has offered hopes of more freedoms at home. If elected, he could try to end crackdowns on liberal media and bloggers and push for Iran to embrace US President Barack Obama's offer of dialogue after a nearly 30-year diplomatic freeze.