By Yeganeh Torbati
DUBAI, June 14 (Reuters) - Iranians began voting on Friday in a presidential election unlikely to result in seismic shifts in its troubled relations with the West and Gulf Arab neighbours, but which could bring a softening of the confrontational style personified by outgoing president Mahmoud Ahmadinejad.
World powers embroiled in talks with Iran over its nuclear programme are looking for signs of a recalibration of its negotiating position after eight years of intransigence under fiery populist Ahmadinejad.
Iran's Gulf Arab neighbours are also wary of Iran's influence in Iraq next door and its backing for President Bashar al-Assad and his Lebanese allies Hezbollah in the Syrian civil war. The Sunni Arab kingdoms are backing the rebels in Syria.
Of five hardline candidates professing unwavering obedience to Supreme Leader Ayatollah Ali Khamenei, three are thought to stand any chance of winning the vote, or making it through to a second round run-off in a week's time.
Of those three main conservative hopefuls only one, current chief nuclear negotiator Saeed Jalili, advocates maintaining Iran's robust, ideologically-driven foreign policy.
The other two, Tehran mayor Mohammad Baqer Qalibaf and former foreign minister Ali Akbar Velayati, have pledged never to back away from pursuing Iran's nuclear programme but have strongly criticised Jalili's inflexible negotiating stance.
They face a single moderate candidate, the only cleric in the race, Hassan Rohani. Though very much an establishment figure, suspicious of the West, Rohani is more likely to pursue a conciliatory foreign policy.
With no independent, reliable opinion polls in Iran, it is hard to gauge the public mood, let alone the extent to which Khamenei and the Revolutionary Guards will exert their powerful influence over the ballot.
State media reported that polling began on schedule at 0330 GMT. Voting lasts for 10 hours, though this can be extended if need be. There are more than 50 million Iranians eligible to vote, 1.6 million of them first-time voters.
But security has been tight and campaigns subdued compared to the euphoric rallies that preceded the last presidential election in 2009, when reformist supporters thought they scented victory and the prospect of change in Iran.
Those hopes were dashed when Ahmadinejad was returned to office by results the reformists said were rigged.
The large street protests that broke out were met with a tough crackdown in which several people were killed and hundreds arrested. The reformist candidates who lost in 2009 are now under house arrest and have little contact with the outside world.
Human rights groups have criticised Iran for further arrests and curbs on activists and journalists ahead of Friday's poll and the disqualification of 678 people registered as candidates, including Akbar Hashemi Rafsanjani, one of the founders of the Islamic Republic.
Iranian officials dispute accusations of human rights abuses and call the charges politically motivated. They also say elections in Iran are free, fair and democratic. (Writing by Jon Hemming, Additional reporting by Zahra Hosseinian, Editing by Andrew Roche and William Maclean)