TEHRAN: Former president and influential cleric Akbar Hashemi Rafsanjani on Friday urged Iranians to come forward and vote in the June 12 presidential election.

"All of us agree that it is in the interest of the system to have an election with massive turnout," he told Tehran's Friday prayer worshippers in a speech broadcast live on state radio.

"Unfortunately there are some who love the system but will not take part because they have some complaints and have not been listened to," said Rafsanjani, head of legislative arbitration body the Expediency Council.

"Logically, rationally and religiously their decision will serve no one. What would you gain by not showing up? It takes a maximum of an hour time to vote, the cost is nothing," he said.

"The day after the poll, when the participation figure is announced, (if it is) more than 70 or 80 percent turnout our system's credibility will rise several rungs in the world," the cleric said.

"And the enemies who want to show that differences exist between the officials and people will have no choice but to pour ashes of shame on their heads," Rafsanjani added.

"I know all of the candidates (and) people with different political inclinations all have a person to vote for, so this opportunity should be harvested," he added.

Iran's electoral watchdog the Guardians Council has cleared hardliner incumbent President Mahmoud Ahmadinejad to stand in the poll along with a fellow conservative, a moderate and a reformist.

The other candidates are former Revolutionary Guards chief Mohsen Rezai, former premier Mir Hossein Mousavi and ex-parliament speaker Mehdi Karroubi.

The final line-up was revealed on Wednesday by Interior Minister Sadeq Mahsouli who also announced the start of the official campaign, lasting until 24 hours before election day.

In the 2001 presidential election, 66 percent of eligible voters cast their ballots and Khatami was reelected in the first round.

In 2005, and for the first time in the history of the Islamic republic, the election was conducted in two rounds since none of the seven candidates secured a majority of more than 50 percent.

In the first round, 62 percent of the eligible voters voted and in the second round 59 percent.

Rafsanjani also urged the state-run broadcaster to "act justly and unbiased" in its coverage of the candidates' campaigns.

In line with the constitution, radio and television broadcasting is a state-run and its chief is appointed by the supreme leader Ayatollah Ali Khamenei.

"Television and radio as the nation's sole broadcaster, gets its credibility from the people's satisfaction and trust. Therefore it should act justly and unbiased during campaigning days," Rafsanjani said.

In a rare move, Iranian television has organised televised debates between the candidates.

Mousavi, seen as Ahmadinejad's leading challenger, has nevertheless accused state television of "repeated and open breaches of neutrality."

Karroubi has previously accused television of broadcasting biased coverage in favour of Ahmadinejad The state media give comprehensive coverage of Ahmadinejad's tours and of his speeches.

Iranian officials have said that 46.2 million Iranians are eligible to vote on June 12. Results are due to be announced the next day.