Hassan Rouhani has won the Iranian presidential election giving the incumbent a mandate to continue efforts to open the Middle East’s second-largest economy up to international investment.

Rouhani fought a fierce campaign against conservative cleric Ebrahim Raisi but emerged with a comfortable lead, winning 57 per cent of the total votes.

Of the 41.2 million votes cast, Rouhani received 23.5 million votes against Raisi’s 15.8 million ballots, according to announcement by Interior Minister Abdolreza Rahmanifazli carried by state TV on 20 May.

The election was a significant test of whether Iranian’s backed the progress of Rouhani, who was instrumental in signing a deal with world powers giving Iran sanctions relief in exchange for limits on its nuclear development programme. The poll was the first test of Rouhani’s popularity since the Joint Comprehensive Plan of Action was signed with six world powers in July 2015.

The lifting of sanctions has opened up the Iranian economy for potential investment but Rouhani’s critics have argued that the agreement has so-far failed to create jobs and improve the economy.

Rouhani campaigned in favour of greater civil liberties and spoke out against the arrests of reformist leaders. Raisi accused Rouhani of mismanaging the economy and called for a harder stance on dealing with the US and other western powers.

US President Donald Trump recently extended the sanctions relief against Iran agreed under the 2015 deal. This, along with Rouhani’s re-election, should give some confidence to companies looking to invest in Iran.

However, Rouhani still faces many of the barriers that have prevented him from delivering significant reforms during his first four-year term.

Although Iran’s present is the key decision-maker, any policies put forward by Rouhani can be vetoed by Supreme Leader Ali Khamenei. Rouhani’s campaign saw him clash with Khamenei’s Revolutionary Guards, warning them not to meddle in the election.

Some commentators have suggested that Rouhani’s election campaign might have heightened disputes with key political institutions in Tehran and make it more difficult for him to push through reforms during his second term.