They are gathering in the holy city of Mecca where they are expected to sign a document drawing on Islamic texts which say shedding Muslim blood is forbidden.
The meeting is being held by the Organization of the Islamic Conference.
Scores of Iraqis are killed on a daily basis in tit-for-tat violence between the Shia and Sunni Muslim communities.
To be displayed
The OIC says the initiative is aimed at quelling religious conflict and cannot hope to achieve reconciliation among Iraq's different communities.
The conference organisers hope that once the document is adopted it will be put on display in mosques throughout Iraq and published in the Iraqi media.
| The most important point in it is that the shedding of Sunni and Shia blood is forbidden, forbidden, forbidden Sheikh Ahmad Abd al-Ghafour al-Samerrai |
Sheikh Ahmad Abd al-Ghafour al-Samerrai, the head of the Sunni Waqf Department in Iraq, told the BBC Arabic service that the Mecca conference is a culmination of previous meetings aimed at putting an end to bloodshed in Iraq:
"A preparatory committee comprised of six scholars met 10 days ago. It issued a communique containing a grand and clear fatwa directed at the Iraqi people forbidding shedding Iraqi blood, killing, threats, kidnapping, etc," he said.
Sheikh Samerrai said that the fatwa, or Islamic religious decree, was made up of seven key points, but he refused to reveal their details.
"We want to surprise the Islamic world with it [the fatwa]. But the most important point in it is that the shedding of Sunni and Shia blood is forbidden, forbidden, forbidden."
BBC Arab affairs analyst Magdi Abdelhadi says the plan would be a good one if it worked, but similar appeals by Sunni and Shia clerics have fallen on deaf ears in the past.