By Parisa Hafezi and Reza Derakhshi
TEHRAN (Reuters) - Former Iranian President Akbar Hashemi Rafsanjani lost his position as head of an important state clerical body on Tuesday, a move which tightens the hardliners' grip on power.
The defeat for one of the great survivors of Iranian politics since the 1979 Islamic revolution highlighted how even establishment opponents of hardline President Mahmoud Ahmadinejad are being isolated and sidelined.
It follows reports by relatives of reformist opposition leaders Mirhossein Mousavi and Mehdi Karoubi, denied by the government, that they have been placed in detention at a secret location to stop them orchestrating pro-reform protests inspired by uprisings in the Arab world.
Security forces fired teargas to disperse anti-government protesters in Tehran on Tuesday, Mousavi's website said.
An ambush challenge by arch hard-liner Ayatollah Mohammad Reza Mahdavi-Kani forced Rafsanjani to withdraw from running for re-election as chairman of the Assembly of Experts.
The 86-member clerical body has the authority to dismiss Iran's Supreme Leader, Ayatollah Ali Khamenei, 71, but it has never exercised that power since it was established in 1983. It also appoints the new leader if the old one is removed or dies.
The vote will not have an immediate practical impact on Iran's complex political structure but analysts said the hardline triumph at the Assembly would further homogenize the establishment by removing another channel for dissent.
"In the short-term Ahmadinejad has scored a victory in terms of his immediate authority within the establishment, but it raises questions for those beyond Rafsanjani who may have questions about that authority," said Professor Scott Lucas, academic and editor of the online journal EA WorldView. "It is a question of who's next?"
Rafsanjani, who had chaired the Assembly since 2007, said he had no intention of causing friction at a time when "discord is becoming very serious" in the Islamic state.
"I regard division at the Assembly as detrimental ... I had said before that should he (Mahdavi-Kani) stand for the position, I would withdraw to prevent any rift," Rafsanjani told the Assembly in a speech, the students news agency ISNA said.
Iranian media said last week that more than 50 Assembly members supported Mahdavi-Kani's candidacy, but the challenger was coy up to the last minute over whether he would run.
The defeat was a blow to Rafsanjani's attempt to play a bridging role between dominant Islamic hardliners and the increasingly marginalized reformist opposition since Ahmadinejad's disputed re-election in 2009.
"THE AGILE CLERIC"
The 2009 vote, which authorities denied rigging as the opposition claimed, jolted Iran with the biggest anti-government street unrest in the past three decades, creating a deepening rift within the Islamic elites.
"There are some (officials) who want to monopolize the leadership ... but it is a major mistake as the supreme leader is above factional politics," said Rafsanjani, in a clear reference to Ahmadinejad and his supporters.
"Ethics have been harmed in society and lies propagate from the level of top officials."
Rafsanjani's political power has been declining since he lost to Ahmadinejad in a 2005 presidential bid and criticized the government's crackdown on the opposition in 2009.
The cleric has faced persistent accusations of corruption and his family has been harassed. His daughter Faezeh, a former lawmaker and a women's rights activist, was briefly detained on a banned rally on February 14, the first street unrest since December 2009 that was crushed by the elite Revolutionary Guards.
His son, Mohsen, resigned as the head of Tehran Metro Company on Friday, citing lack of financial support from the government. Another son, Mehdi, faces arrest if he ever returns to Iran on accusations of fomenting unrest in 2009.
Rafsanjani still heads the Expediency Council, an unelected arbitration body that resolves disputes between parliament and a clerical vetting body, the Guardian Council.
Some analysts still believe the agile cleric may still bounce back by using residual influence in some layers of the Revolutionary Guards and among top clerics, who see him as a pillar of the Islamic revolution able to defuse crisis.
Rafsanjani, with a political career spanning more than half a century, has held most of the top positions in Iran's political structure including parliament speaker, armed forces commander and president from 1989 to 1997.
He has also been at the heart of almost every key moment in the 32-year-old Islamic republic's life, including decisions to prolong and then end the 1980-1988 war with Iraq, as well as covert arms-for-hostages deals with Washington in the 1980s.
(Additional reporting by Hashem Kalantari; Writing by Parisa Hafezi Editing by Paul Taylor and Jon Hemming)