NAJAF, Iraq, Aug 25 (AFP) - Grand Ayatollah Ali al-Sistani, Iraq's revered Shiite spiritual leader who returned home Wednesday to lead a campaign to "save" the holy city of Najaf, has always hidden behind an arcane and near-impenetrable curtain of Shiite Muslim ritual and austerity.
He flew back Wednesday from London, where he went for medical treatment three weeks ago just as fighting broke out between militia loyal to radical Shiite cleric Moqtada Sadr holed up in and around the shrine of Imam Ali, and US and Iraqi forces.
Those forces threatened Wednesday to wrest control of the shrine at the risk of damaging the building and offending the sensibilities of millions of Shiite Muslims.
Normally, Sistani rarely strays from a humble office at the end of a dusty lane, blocked off and patrolled by armed guards, in Najaf, 180 kilometres (110 miles) south of Baghdad and one of the holiest Shiite pilgrimage sites.
Since the fall in April last year of Saddam Hussein's regime, which muzzled the Shiite hierarchy in Iraq, senior officials from the Governing Council, the US-led coalition, the United Nations, the Arab League and, latterly, the interim government, all came to Najaf to try to win Sistani's approval.
Sistani arrived in Najaf as a religious student at the age of 21, but his reclusive nature is said to stem from his years trying to operate under Saddam when he was under house arrest and he was long considered apolitical.
Though born in Iran, he has little time for the neighboring Islamic republic's Shiite theocracy.
However the 73-year-old cleric underwent a remarkable transformation since US-led forces invaded Iraq and, until the formation of the interim government at the end of June, emerged as a national leader by default.
The grey-bearded Sistani, one of only five living grand ayatollahs, inspires awe in Iraq's 15 million Shiites, based on their reverence for tradition, while the country's politicians scramble for a broad-based following.
As the US-led coalition authority struggled to get to grips with the business of handing over power, Sistani embarrassed it when he instigated a walk out by five Shiite council members at the elaborate signing ceremony for the country's interim constitution.
The cleric raised alarm over a provision allowing Iraq's Kurdish minority to hold an indirect veto over the permanent constitution to be drafted next year and insisted the Shiites exercise total control of the country's presidency.
He also threatened nationwide protests if polls were not held to pick the transitional government to take office on June 30, but accepted the findings of a UN mission that ruled out early elections.
But Sistani's decision-making process is filled with mystery and little is known about what really goes on in his spartan home in the heavily guarded alley.
Guests sit on the floor and meet with the cleric's son Mohammed Rida while they wait for him to enter.
His decisions have marked a U-turn in policy from the teachings of his mentor, Grand Ayatollah Abdul Qassim al-Khoie, who died in 1992.
Sistani is said to fear squandering Iraqi Shiites' first real shot at power since the then occupier, Britain, marginalised them in 1920 after Shiite tribes revolted against the presence of foreign troops.