Former Iraqi Prime Minister Iyad Allawi says a group tried to kill him during a visit to an important Shia shrine in the central city of Najaf.
Mr Allawi was in Najaf on the campaign trail
Police said earlier that a crowd of people threw rocks and shoes at Mr Allawi and that his bodyguards had fired in the air in response.
Mr Allawi is a secular Shia who is challenging the governing Shia Islamist bloc in parliamentary polls next week.
TV footage showed his group fleeing the shrine as shoes were thrown at them.
This is viewed as a major insult in Arab culture.
Correspondents say the clash is another sign of the bitterness of divisions within Iraq.
Mr Allawi is trying to portray himself as a unifier of Shia and Sunni Muslims, but he has political enemies among his own community, says the BBC's Caroline Hawley in Baghdad.
'Planning to kill'
The politician was in Iraq's holiest city for Shias on the campaign trail.
He said about 60 people, some armed with pistols and knives, approached his group as they prayed at the shrine of Imam Ali.
"They were planning to kill the whole delegation, or at least me," Mr Allawi told reporters on his return to Baghdad.
"One of them took out his pistol, but he panicked and it fell from his hand," he said.
The former US-backed leader has survived several attempts on his life.
He was interim prime minister when US troops seized control of Najaf from followers of the radical Shia cleric Moqtada Sadr in 2004. They handed over military control of the city to Iraqi forces in September.
Mr Allawi stepped down in April after a January election gave a majority to the Shia United Iraqi Alliance.