BAGHDAD -- Explosions killed at least 26 people across Iraq on Thursday, most of them Shiite pilgrims taking part in a holy mourning ceremony, authorities said, raising fears of further sectarian attacks at the approach of Shiite Islam's most solemn occasion.

The deaths came three days before the climax of Ashoura, when hundreds of thousands of Shiite pilgrims converge on the central city of Karbala to mourn the killing of the Prophet Muhammad's grandson, Imam Hussein, in a 680 A.D. battle that sealed the split between Shiites and Sunnis.