Iran's week-long parliamentary election campaign began on Thursday, the official IRNA news agency said, a vote likely to highlight the popularity of the clerical establishment as it stands firm against Western pressure to curb its nuclear work.

It is shaping up as a contest among clerical and political conservatives on March 2, the first nationwide vote since the disputed 2009 re-election of President Mahmoud Ahmadinejad that sparked eight months of unrest and a crushing state response.

With a no-show by leading pro-reform groups, loyalists of Iran's most powerful figure, Supreme Leader Ayatollah Ali Khamenei, and backers of Ahmadinejad, who is not a cleric, will compete for a majority of the 290-seat parliament.

Khamenei's supporters, sharply critical of Ahmadinejad's economic policies, look set to win the vote as international sanctions imposed over Tehran's disputed nuclear programme make life harder for ordinary Iranians.

The 3,444 candidates running for parliamentary elections have started the campaigning by mainly handing out fliers and raising posters on Thursday, IRNA reported.

The streets of Tehran lacked the lively mood of an election. There were sporadic banners in some major squares and streets but most of them bore pictures of Khamenei, as both camps were trying to take advantage of his popularity to attract votes.

Organizing the country requires a capable parliament which can be achieved by active participation in elections, read a purple banner in central Tehran.

More than 48 million Iranians are eligible to vote.

Pro-reform groups decided to maintain a low profile by keeping leading figures out of the vote, saying their demand for a free and fair election was not fulfilled.

The candidacies of some 35 percent of those who sought to run for parliament were rejected by the Guardian Council, a powerful vetting body made up of six clerics and six jurists. Many Ahmadinejad supporters were barred, politicians say.

REFORMIST LEADERS MARGINALISED

Leaders of Iran's pro-reform opposition have been sidelined since the 2009 vote, with two of them, Mirhossein Mousavi and Mehdi Karoubi, under house arrest since February 2011.

Mousavi and Karoubi both lost to Ahmadinejad in the 2009 vote and insist it was rigged to secure his re-election.

Khamenei swiftly endorsed Ahmadinejad's return to power but a rift between the two leaders opened up after the president tried to gain more power by undermining the role of the clergy in the Islamic Republic.

The rift surfaced in April when Khamenei reinstated an intelligence minister Ahmadinejad had sacked.

Debates among political figures have started on state television, focusing mainly on the fading economy whose troubles have been blamed on Ahmadinejad's cuts in food and fuel subsidies as well as Western sanctions aimed at forcing Tehran to halt its uranium enrichment programme.

Parliament speaker Ali Larijani, a hardline rival of Ahmadinejad, called on candidates to avoid disappointing people with critical debates and campaigning.

The international situation and people's living conditions have brought about enough hopelessness. Candidates should encourage people to the polls by creating hope among them, the Arman daily quoted him on Thursday as saying.

Prices of goods have spiralled in recent weeks because of the plummeting value of the Iranian currency, the rial, and the squeeze from international sanctions on Iran's financial institutions imposed over its nuclear programme.

(Writing by Zahra Hosseinian, Editing by Mark Heinrich)