One of Iran’s most prominent dissident clerics, Grand Ayatollah Hoseyn Ali Montazeri, has died aged 87.

“Hoseyn Ali Montazeri passed away in his home last night,” state-owned Irna news agency said.

Hoseyn Ali Montazeri was a moving spirit in the 1979 revolution which created Iran’s Islamic state, and was at one stage set to become its leader.

One of Shia Islam’s most respected figures, he was also a leading critic of President Mahmoud Ahmadinejad.

Grand Ayatollah Montazeri issued a fatwa condemning President Ahmadinejad’s government after June’s disputed election.

‘Sense of religious duty’

But that was not his first clash with authority. He repeatedly accused the country’s rulers of imposing dictatorship in the name of Islam.

During his lifetime, the cleric was transformed from a pillar of the Islamic revolution to one of the most vocal critics of its leadership.

Grand Ayatollah Montazeri became an inspiration for reformists

He had been designated to succeed the Islamic Republic’s founder, Ayatollah Ruhollah Khomeini, but the pair fell out over Iran’s human rights record a few months before Khomeini died of cancer in 1989.

Montazeri then spent six years under house arrest.

In 1997 he famously clashed with Ayatollah Khomeini’s successor, Ayatollah Ali Khamenei, after questioning the powers of the Supreme Leader.

This led to the closure of Grand Ayatollah Montazeri’s religious school, an attack on his office in Qom and a period of house arrest.

Born into a provincial family and educated at a seminary, Hoseyn Ali Montazeri came to prominence as one of the early supporters of Imam Khomeini.

Prior to the overthrow of the Iranian monarchy, he organised public protests in support of Imam Khomeini, following the latter’s arrest.

As a result Grand Ayatollah Montazeri was repeatedly detained himself and tortured in jail.

While Imam Khomeini was in exile in Iraq, Grand Ayatollah Montazeri was nominated as his representative in Iran, and after the revolution, he was designated as successor.

But he was marginalised after questioning decisions taken by the Supreme Leader and calling for a transparent assessment of the revolution’s failures.

In his opposition to President Ahmadinejad, he became an unlikely inspiration for Iranian reformists.

Despite his old age and failing health, Hoseyn Ali Montazeri backed the opposition’s claims that the 2009 election result, which gave President Ahmadinejad a landslide victory, had been widely rigged.

The cleric had often said his opinions were guided by his “sense of religious duty”.