NAJAF, Feb 5: The revered spiritual leader of Iraq's Shia majority, Grand Ayatollah Ali al-Sistani, escaped an assassination attempt on Thursday, his office said , as the United Nations prepared to send a mission to review his political demands.

A man tried to break into ayatollah's office to carry out "a criminal act targeting" the cleric, but was caught by his bodyguards, one source close to his office told AFP.

The ayatollah escaped unharmed, the source added.

The report, which could not be immediately confirmed, contradicted television reports that gunmen sprayed ayatollah's car with bullets as he left his office for home.

The reclusive and gaunt 73-year-old Sistani lives and works in the same compound, patrolled by armed guards, near the shrine of Imam Ali.

By late Thursday, the streets around the compound were quiet, an AFP correspondent said.

Shia politician Muaffak al-Rubei said the ayatollah was safe and sound, after meeting him in Najaf.

"I just met Sayyed Sistani, he is safe and sound," said Mr Rubei, a member of Iraq's US-appointed interim leadership. "He is surrounded by his relatives who are taking care of him.

"These violent acts should be condemned against any of our leaders, whether political or spiritual," he said.

Mr Rubei said he doubted sectarian strife would break out because of "Iraqi awareness of the need to preserve the unity of the country".

A Sunni member of the Governing Council immediately denounced the attack.

"This horrible act aims only to divide the Iraqi people but it will fail," said Nasir Chaderchi.

Asked whether Ayatollah Sistani's insistence on elections could have been behind the assassination attempt, Mr Chaderchi said: "Everyone wants elections in Iraq, some want them before the transfer of power and some after."

Ayatollah Sistani hails from the quietest school of Shia thought that counsels against religious leaders' involvement in politics.

An Iranian by birth, he moved to Najaf in 1952 to dedicate his life as an Islamic scholar.

Speaking before the assassination attempt, a top US military official in Iraq recognized there was "serious cause for concern" about rumblings of ethnic discontent in the country.

"I think there is some serious cause for concern there ... especially as we get closer and closer to governance," the source told AFP in an interview on Wednesday.

"There's a healthy debate going on but when it crosses from healthy debate into violence we're going to take action."

Despite stressing that coalition troops were presiding over a "safe and secure Iraq", he said the post-war situation contributed to an "element of chaos" in the country.

Thursday's incident came just a day before a team of UN experts was expected in Baghdad to assess the feasibility of Ayatollah Sistani's demand for elections to Iraq's first post- occupation government, which is due to be installed by the end of June.

UN Secretary-General Kofi Annan ordered the mission at the request of the US-led coalition after it failed to broker a compromise deal to maintain its tight timetable for the handover of power.

OPPOSITION TO US: In recent months, Ayatollah Sistani has spoken out against US proposals for transferring power to an Iraqi government by July 1, saying he wants direct elections to be held rather than the US plan for a system of indirect regional caucuses.

The ayatollah's pronouncements carry enormous weight in Iraq and his opposition to the US power transfer plans has thrown into question whether sovereignty will be returned by the deadline.

He seldom makes political statements and is regarded as a low-profile but influential religious leader. Given his huge following, his increasingly politicized role has turned him into possibly the most powerful man in postwar Iraq.

His words recently sent thousands of Shias into the streets to protest against the US power transfer plans.

The cleric has received UN envoys in the past and kept open a dialogue with the international body, but he has refused to meet US officials, including the US-appointed governor in Iraq, Paul Bremer, for fear of appearing too close to the US-led occupation.-Agencies