Driven by growing interest from young voters, a Huge turnout in Iran presidential poll is expected:
There has been a huge turnout for Iran’s closely-fought election as incumbent President Mahmoud Ahmadinejad seeks a second term in office.
“Voter turnout has been unprecedented,” election commission chief Kamran Daneshjoo said, as long queues were reported at polling stations.
Polling has been extended by three hours to 2100 local time (1630 GMT).
Mr Ahmadinejad faces a strong challenge from former PM Mir Hossein Mousavi in a campaign dominated by the economy.
The election is being watched closely around the world for signs of a possible shift in Tehran’s attitude.
US President Barack Obama said he was “excited” about the robust debate taking place, which showed change was possible in Iran.
Four candidates are contesting the election, with Mohsen Razai and Mehdi Karroubi trailing the two main contenders.
In his final TV appearance before the election, Mahmoud Ahmadinejad accused his opponents of conspiring with Israelis to falsify documents and graphs to discredit him.
His rivals boycotted the chance to appear on TV with him, after apparently not being offered equal airtime.
The result will be watched closely outside Iran – in the US, Israel, and European capitals – for any hint of a possible shift in the country’s attitude to the rest of the world, BBC diplomatic correspondent Jonathan Marcus says.
The timing of the election is also crucial, as the US push for a new policy of engagement with Tehran cannot really get going until the outcome of the election is clear, our correspondent adds.
The live TV debates unleashed enthusiasm among the country’s young population.
BBC Iranian affairs analyst Sadeq Saba says most of them appear to be supporting the moderate candidate, Mir Hossein Mousavi.
President Ahmadinejad draws support mainly from the urban poor and rural areas, while his rivals have huge support among the middle classes and the educated urban population.
Iranian women have also shown great interest in the election and it appears many of them will be voting for the moderate candidates who have promised them more social freedoms, our analyst says.
The votes in regions with national and religious minorities are also important, as they normally vote for reformist candidates.
Mr Mousavi is an ethnic Azeri and is expected to do well in his province, as is Mahdi Karrubi in his native Lorestan province.
Iran is ruled under a system known as Velayat-e Faqih, or “Rule by the Supreme Jurist”, who is currently Ayatollah Ali Khamenei.
It was adopted by an overwhelming majority in 1979 following the Islamic revolution which overthrew the autocratic Western-backed Shah.
But the constitution also stipulates that the people are the source of power and the country holds phased presidential and parliamentary elections every four years.
All candidates are vetted by the powerful conservative-controlled Guardian Council, which also has the power to veto legislation it deems inconsistent with revolutionary principles.
People need to know that the Iranian President has negligibly little powers. As explained above, all major powers are with the Rahbare Enghelab (Revolutionary Leader), an office that is currently held by Ayatollah Khamenei.
An overhaul of the Iranian system will happen sooner or later. It is certainly a possibility that Iranians, too, will vote for change this time. How soon we will see real change remains to be seen. Whatever the turnout will be, there is certainly reason to hope for a more engaged dialogue between Iran and the West moving forward.
Here are the current Intrade.com Percentages: