NAJAF, Feb 6: An attack on Iraq's most revered Shia leader was shrouded in mystery on Friday, as some in his entourage swore it was an attempt to kill him while others denied it had any murderous intent.

"Sayyed (leader) Sistani escaped an assassination attempt on Thursday in Najaf," one of the spiritual leader's security team in this central pilgrimage city said.

A source close to Grand Ayatollah Ali al Sistani said a man tried to break into his office to carry out "a criminal act targeting" him, but was caught by his bodyguards.

The first to break the news on Thursday, Shia politician Muwaffaq al Rubaie, immediately appealed to his co-religionists not to attack Sunnis and said the 73-year-old cleric leader was being cared for by his relatives.

"What I call for now, is for there to be no confessional backlash after this assassination attempt. Instead there should be a national response encompassing all of Iraq," said Mr Rubaie, a member of the US-installed Governing Council. But on Friday he changed his tune.

"What I can say is that Sayyed Sistani is is good health, he is unharmed," said Mr Rubaie, refusing to confirm or deny reports of an attempt to kill Ayatollah Sistani.

Neither was anyone talking outside the ayatollah's office in Najaf, 160 kilometres south of Baghdad. "It was nothing. Nothing happened," said a plainclothes man standing in front of the security barrier at the entrance to the street where Sistani lives and works. -AFP