The vote pitches a divided conservative camp against a moderate candidate who enjoys the backing of the reformists. Iranian supreme leader Ayatollah Ali Khamenei, who votes in the earliest moments after the opening of the polls, urged people to vote en masse.

"Inshallah (God willing), the Iranian people will create a new political epic. I advise all people to vote and do so in the early hours of the morning," said the Iranian leader in a live broadcast on state television. He also attacked US criticism of the presidential poll. Some US officials had said they did not recognise the presidential election, he noted. "The hell with you... " who do not agree with the way the election is being run, Khamenei said.