The reformist-backed Hassan Rouhani has won Iran’s presidential election, receiving just over half of the vote to narrowly avoid a run-off.

Mr Rouhani, who will succeed Mahmoud Ahmadinejad, mobilised the moderate vote after Mohammad Reza Aref, the sole reformist candidate, withdrew from the race on Tuesday.

Tens of thousands gathered in the capital Tehran to celebrate the former lawyer’s victory, chanting “long live Rouhani”, with the President-elect proclaiming a “victory of moderation over extremism”.

Mr Rouhani went on to say: “A new opportunity has been created for those who truly respect democracy, interaction and free dialogue.”

Israeli Prime Minister Benjamin Netanyahu called for continued vigilance, declaring that “the international community should not fall into wishful thinking and be tempted to ease pressure on Iran to stop its nuclear programme”.

The American government’s reaction, however, was cautiously optimistic. Mr Rouhani’s triumph over an otherwise conservative field prompted White House Chief of Staff Denis McDonough to say “if [Rouhani] lives up to his obligations under the UN Security Council resolutions to come clean on this illicit nuclear programme, he will find a partner in us”.

The turnout was high at 72 per cent, though this was down on the 85 per cent who cast their ballots in 2009. Rouhani garnered 50.71 per cent of the 36.7 million votes cast, according to Interior Minister Mostafa Mohammad Najjar, with Tehran Mayor Mohammad Baqer Qalibaf placing a distant second on 16.56 per cent.