Iraq's holy city of Karbala has been crowded with millions of Shi'ite Muslims for one of their biggest annual events, which was largely free of mass violence this year.
The Arbain event often causes gridlock in Baghdad and much of southern Iraq as several major highways are reserved for pilgrims travelling on foot to Karbala.
Arbain means "40" in Arabic. December 3 marked the end of a 40-day mourning period for the seventh-century martyrdom of Imam Hussein, a central figure in Shi'ite Islam and the Prophet Muhammad's grandson.
"More than 20 million pilgrims, among them 5 million Arabs and foreigners, took part in the pilgrimage," Staff Major General Qais Khalaf told a news conference in Karbala.
He said 25,000 Iraqi security personnel, with help from Iranian counterparts, were successful in preventing extremist attacks like those that have killed hundreds during previous pilgrimages.
The Baghdad security command said security forces killed two suicide bombers before they could attack pilgrims. At least six people were killed in Baghdad on November 30, however, in two separate attacks targeting marching pilgrims.