Bombs have exploded in cities across Iraq as Shi'ite Muslims gathered for annual religious processions. Iraqi authorities say at least 46 people were killed in one of the country's deadliest waves of violence this year.

They said four bombs targeted Shi'ite pilgrims in and around Baghdad, killing at least 19 people, while car bombs killed at least five people in the mainly Shi'ite town of Balad to the north.

Officials said bombs also exploded in the central city of Hilla, killing at least 21 people, and the northern city of Kirkuk, killing at least one. Other deadly bombings were reported in the towns of Taji, Baquba, Azizyah and Karbala.

Iraqi Shi'ite pilgrims have been gathering in major cities for processions to commemorate the death of a revered 8th century imam. Minority Sunni insurgents have repeatedly bombed such processions in the past.

The latest bombings also coincide with an Iraqi political crisis in which minority Sunni and Kurdish lawmakers have been trying to unseat Shi'ite Prime Minister Nour al-Maliki, accusing him of monopolizing power in Shi'ite hands.

Violence in Iraq has declined significantly since its peak in 2006 to 2007, but attacks remain common, especially in Baghdad.