Officials have announced that a moderate cleric will square off against a hard line mayor in Iran's first ever run-off presidential election next week.

In the voting, held on Friday, Akbar Hashemi Rafsanjani was in front with 21 percent of the 29 million votes cast. In second place, Mahoum Ahmadinejad held 19 percent of the vote.

 If a candidate fails to secure the 50 per cent support required for an outright victory, another round of elections must take place. Voters must now choose between Rafsanjani, who has pledged better ties with the U.S. and Canada and was considered the favourite to win; and Tehran mayor Ahmadinejad, who has expressed resistance to re-opening talks with the West and has a reputation of being a man of the people.