Moderate cleric Hassan Rouhani was declared Iran's new president in a surprise outright election victory that ends eight years of conservative grip on the top office.

Rouhani, 64, has been deputy speaker of the Islamic Consultative Assembly, and he was also heading Iran's former nuclear negotiating team and was the country's top negotiator on the Iran's nuclear program between the years 2003-2005.

His leading role in the nuclear negotiations brought him the nickname of "diplomat Sheikh".

When Rouhani was top nuclear negotiator under Khatami, the Islamic republic agreed to suspend its controversial enrichment of uranium.

But that program resumed when Ahmadinejad was first elected.

Rouhani, who favors a policy of political openness, as well as re-establishing relations with the west, is likely to soothe international tension. Rouhani has vowed to restore diplomatic ties with arch-foe the United States.

His moderation provokes conservatives who accuse him of being influenced by Britain's former foreign secretary Jack Straw's perfume and tie with whom he held talks in 2003.