Iran expects a record number of voters to cast their ballots in this week''s presidential election, the head of the country''s election committee has said.

"Definitely, the election... will witness a record-breaking turnout," Kamran Daneshjoo told reporters on Monday ahead of Friday''s vote.

Daneshjoo said the interior ministry, which is in charge of organising the election, is putting in place a strategy to ensure "maximum participation" from the 46.2 million eligible voters.

Four candidates are in the race for the presidency, including incumbent hardline President Mahmoud Ahmadinejad, who is seeking a second four-year term.

He faces stiff a challenge from ex-premier Mir Hossein Mousavi who has emerged as his main rival.

The two other candidates are reformist former parliament speaker Mehdi Karroubi and ex-head of the elite Revolutionary Guards Corps, Mohsen Rezai.