Loyalists of Iran's paramount clerical leader have won over 75 per cent of seats in parliamentary polls, a near-complete count showed, largely reducing President Mahmoud Ahmadinejad to a lame duck in a contest between conservative hardline factions.

The outcome of Friday's vote, largely shunned by reformists whose leaders are under house arrest, will have no major impact on Iran's foreign policy including its nuclear dispute with the West.

But it will give Supreme Leader Ayatollah Ali Khamenei's camp a significant edge in the 2013 presidential election.

The widespread defeat of Ahmadinejad's supporters was likely to erode the authority of the president, under fire from Khamenei's allies for challenging the utmost authority of the supreme leader in Iran's multi-layered ruling hierarchy.

With 90 per cent of ballot boxes counted, Khamenei acolytes were expected to occupy more than three-quarters of the 290 seats in the Majlis (parliament), according to a list published by the interior ministry.

In the race for the 30 seats in the Islamic Republic's capital Tehran, a Reuters tally of unofficial preliminary returns showed Khamenei supporters had taken 19 and pro-Ahmadinejad candidates the rest.

Pro-Khamenei candidates won in the Shi'ite Muslim holy cities of Qom and Mashhad and were leading in other major provincial cities like Isfahan and Tabriz, where over 90 per cent of voters backed Ahmadinejad in the 2009 parliamentary poll.

Even in rural areas that have been strongholds of Ahmadinejad's and his populist brand of non-clerical nationalism, Khamenei loyalists appeared to have swept around 70 per cent of the seats.

Independents and women candidates fared relatively well in many provincial towns, where they campaigned on the immediate concerns - generally economic - of their constituents.

Iran's energy-driven economy is suffering badly from Western sanctions - now expanding to block its lucrative oil exports - imposed over its refusal to halt sensitive nuclear activity and open up to UN nuclear inspectors.

Final election returns are expected by Monday.

The results are hard to compare with the outgoing parliament since Khamenei and Ahmadinejad loyalists were united in the 2008 elections, garnering about 70 per cent of seats.

But analysts said the combative Ahmadinejad, who is constitutionally barred from running for a third term, would not readily bow to the rout of his supporters and may fight back.

'Ahmadinejad's camp has not been demolished. We have to wait and see what happens after the new parliament convenes in June,' said analyst Hamid Farahvashian.

'The vote showed that there is a deepening rift between the ruling elites. It might emerge in the coming weeks.'

Ahmadinejad is likely to be summoned to an unprecedented hearing in the outgoing parliament by Friday to answer questions about his handling of the economy and foreign policy.

Some critics say he has inflicted higher inflation on Iranians by slashing food and fuel subsidies and replacing them with cash handouts of about $38 a month per person.

Parliament could impeach Ahmadinejad if his explanations are unconvincing, but Khamenei's green light would be needed.

Analysts said Ahmadinejad is likely to survive his term - but as a lame duck president.

'The establishment is under Western pressure and does not want to look divided,' said analyst Babak Sadeghi. 'Ahmadinejad will finish his term as a weak executive.'

Under mounting Western pressure over its nuclear programme and concerns that Israel might attack, Iran's clerical elite needed a high election turnout to shore up their legitimacy damaged since Ahmadinejad's 2009 re-election, in which fraud allegations triggered eight months of anti-government protests.

Khamenei, 72, said a high turnout would be a message of defiance to 'the arrogant powers bullying us', a reference to Western states and sanctions against Iran.

State officials said the turnout was over 64 per cent, higher than the 57 per cent in the 2008 parliamentary vote.

Absent from the vote were the two main opposition leaders. Mirhossein Mousavi and Mehdi Karoubi, who ran for president in 2009, have been under house arrest for more than a year.

Iran denies Western suspicions that it is enriching uranium with the ultimate goal of developing nuclear weapons, saying the programme is for peaceful energy only.

But arch-adversary Israel has talked of war if diplomacy and sanctions do not bring about a peaceful outcome to the nuclear row.

Iran will top the agenda when Israel's prime minister meets US President Barack Obama in Washington on Monday.

Obama also said military action was among the options to prevent Iran acquiring nuclear weapons. But he also argued against a pre-emptive Israeli strike.

Global oil prices have spiked to 10-month highs on tensions between the West and Iran, Opec's second biggest crude producer.-Reuters