Riding a large turnout from Iran’s urban middle classes, President Hassan Rouhani on Saturday won re-election in a landslide, giving him a mandate to continue his quest to expand personal freedoms and open the country's ailing economy to global investors.

This resounding victory should enable him to strengthen the position of the moderate and reformist faction as the country prepares for the end of the rule of the 78-year-old supreme leader, Ayatollah Ali Khamenei, reported The New York Times.

Of the 41 million votes cast, the Interior Ministry said, Rouhani won 23 million (or 57 per cent), soundly defeating his chief opponent, Ebrahim Raisi, who received 15.7 million (38.5 per cent).

Turnout was heavy, with more than 70 per cent of Iran’s 56 million voters casting ballots, said the report.

Despite the healthy margin of victory, Rouhani, 68, will face considerable headwinds, both at home and abroad, as he embarks on his second term, it added.