With more than 80 per cent of the votes counted, election officials said that Mahmoud Ahmadinejad, 49, held a commanding lead of 61 per cent over his reformist rival, Hojatoleslam Ali Akbar Hashemi Rafsanjani, 70.

The Interior Ministry declared Mr Ahmadinejad the winner. “Poor provinces have voted massively for Ahmadinejad,” an unnamed ministry official said.

With five candidates knocked out in the first round of voting last week, the run-off pitted Mr Ahmadinejad, against Hojatoleslam Rafsanjani, a restyled reformist and former president. Reformists had pinned their hopes on the young people who initially boycotted the election voting to block Mr Ahmadinejad, whose proposed punishment for criminals is to chop off their hands. “This is a fight between reformists and conservatives,” said Nafisa, a 21-year-old student, as she cast her ballot at Fakhrabad Mosque in Tehran.

“I didn’t vote last time as I didn’t believe in it. Now everyone is saying that Ahmadinejad might win so all my friends are voting for Rafsanjani. It’s the difference between bad and worst.”

Although polls were extended by four hours, turnout was lower than last week. Officials said that 22 million, or 47 per cent, had voted, well down on the turnout of 63 per cent in the first round a week ago.

The mayor shocked rivals by his sudden ascent in the first round. The religious conservative has the support of the regime and has captured the attention of the Iranian poor with his ascetic message of socialist-style economic reform and cultural discipline.

His campaigning has been a stroke of genius. The slick, Western-style campaigns of the other candidates backfired, alienating working-class voters who were not impressed by colourful posters and abstract talk of modernisation.

In contrast, Mr Ahmadinejad played up his humble origins and sold himself as a man of the people.

Campaign leaflets showed him sitting cross-legged on a Persian rug eating a modest meal of bread and cheese promising to solve poverty, unemployment and corruption.

“We need a fundamentalist running the country,” said Ali, 28, a university teacher. “We have corruption and many cultural problems here. The US cultural attack in Iran, using the internet and satellite TV has caused many difficulties. We need Ahmadinejad to put us back in place.”

Mr Ahmadinejad’s critics predicted that a victory for his fundamentalist Islamic values would mean a return to the dark days of the regime, when flogging and imprisonment for petty crimes— such as mixing with the opposite sex and wearing make-up — were common.

“I never thought I’d vote in my life,” said Kayvan, a businessman who imports food. “But if Ahmadinejad gets in, I’m going to have to leave Iran.”

Iran’s Supreme Leader, Ayatollah Ali Khamenei, has banned all victory celebrations. “Dragging people on to the streets . . . under any pretext is against the interests of the country,” he declared.

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