Government figures close to Prime Minister Nouri al-Maliki told the Los Angeles Times the deaths at a Sunni protest encampment Tuesday were triggered by militants who opened fire when Iraqi forces entered the camp.
However, Sunni politicians said government forces shot at demonstrators without being provoked.
The violence in the Sunni town of Hawija spread to three other towns leaving at least 36 people dead and nearly 100 wounded.
Members of both political factions agree that if the government can't bring calm to the county, a Sunni uprising could result and merge with the war across the border in Syria.
Observers told the Times that Tuesday's violence was the culmination of the ill will that has colored Iraq's political process since 2008.
Iraq's ruling Shiites have failed to share power equitably with the Sunni minority, who enjoyed privilege under the late dictator Saddam Hussein.